Overall Score: 90/100

HiBy RS6 Review – Portable R-2R Goodness

My Video Review:

There’s always a first time for everything in life. In my case, I’m meeting Hiby Music and all their doings and in case of Hiby Music (Hiby from now on), they just finished working on a very different portable digital audio player.

You probably heard about their portable DAPs and Bluetooth gizmos by now, they’re literally everywhere. Even Hiby Music and Hiby Blue software are extremely popular among Hiby’s own portable players and you can find them on many other platforms…as you can install them on unlocked Android devices. Their Hiby Link two-way Bluetooth controller was so popular, that many companies started copying its features, releasing their own remotes. If you give it a search, people still use it today in tandem with portable DAPs of Shanling, Cayin, Tempotec, Questyle and Hidizs.

With 20 years of experience under their belts mostly in the portable audio field, a time came to unleash their geniuses, crafting a very different DAP and cementing themselves as road openers for R-2R and FPGA technology to be used in a portable device. The biggest splashes are making the tallest waves and that’s why behind closed doors Hiby went all-in with R&D, coming out with quite a special digital audio player that I will be testing today. I don’t remember ever trying an R-2R ladder DAP infused with a freshly developed Darwin architecture that provides a plethora of tuning options, so you can make it your own. Arming it with a speedy SoC and spotting a Direct Transport Architecture, a full MQA decoder, adjustable FIR filters, an OS/NOS mode, tens of plugins and many other sound enhancements, RS6 is not your off-the-shelf DAP, but a very different one from multiple points of view. Hiby’s RS6 goes for $1399 and it’s time to check if it’s worth it or not.

Unboxing Experience

Everything came double boxed as an extra protection measure, thicker card-board boxes have been used, there is plenty of foam that will surely protect the precious cargo during shipping and it seems that Hiby prepared an outstanding unboxing experience. Upon opening up its case a message is being revealed, as their goal is to Make Music More Musical. I’ve raised my right hand as I’m with them on this brave quest.

Hiby provided plenty of accessories for casual and seasoned audiophiles alike. The unit itself is being protected by thick layers of foam, below it you’ll find a small accessory compartment that holds a high-quality USB type-B to Type-C cable that is wrapped in a nylon jacket, another USB Type-C to Coaxial (RCA connector) cable can be spotted – just in case you’ll want to use it as a digital transport. Going deeper, a really nice leather case is being revealed which makes me extremely happy, knowing that everything I need is already in the package. The finishing touches will be provided by two screen protectors, by a warranty card and by a Quick Start Guide.

I can’t get my eyes from that beautiful leather case that fits it like a glove. It’s masterfully made, I find it thick enough, it’s smooth on the outside and soft on the inside thanks to a velour padding. I don’t think you’ll ever need a third-party case, as the preinstalled one looks and feels outstanding. This is everything you’ll find inside its package, just add a big capacity micro-SD card or connect wirelessly to your favorite streaming app and you’re ready to rock!

Design & Build Quality

I appreciate that Hiby is sticking with a time-tested design that can be found on their latest DAPs as New R6 and R8, but what I like the most about RS6 is that you’ll find buttons only on its right side. After touching and playing with it for about two weeks, I’m liking its minimalist layout, as I never missed a button when going outside for a walk. I have bigger hands, so finding and pressing blindly the next or the previous buttons felt easier to say a FiiO M15 or M17. RS6 looks a little different to other DAPs that passed through my hands, adding coolness and uniqueness to it. It gained 80 grams compared to New R6, making it feel solid and tight in the hand. If you’re familiar with the layout of New R6 and R8, then RS6 would feel like the same unit. You need exactly a minute to learn its buttons, inputs and outputs and I wish other DAP manufacturers offered the same learning curve. Try doing that with the latest FiiO devices, as you’ll need at least a day to readjust to the newest button layout.

Having only four buttons and a volume wheel is a huge problem solver when jogging outside, as there’s only an On/Off, play/pause, next and previous buttons, a volume wheel and that’s it! I don’t think it can get any simpler than this. Instead of using a machined aluminum alloy case, Hiby went one step further and exchanged it with a pure copper case, that added a considerable weight to it. While being on the heavier side to New R6, it added confidence that I’m dealing with a higher-tiered DAP. I must confess that its official pictures aren’t doing it justice, as its sandblasted copper case looks and feels absolutely gorgeous. Besides its full copper roll-cage, you’ll find a glass sheet on top that was cut to its body shape and a carbon-fiber look was added on its back. Its ~5” screen looks bezel-less compared to several current-production DAPs, making a stunning first impression. There’s just a screen on its front panel, adding to the immersion and making it look modern and in line with today’s smartphone trends.

Hiby Music, Hi-Res, Hi-Res Wireless and DSD logos are staying behind a glass sheet, adding some high-end flair to it…which is already a common practice with top-grade DAPs. Another interesting aspect is that its volume wheel isn’t sticking out, as it sits on the same level with its upper body, so you won’t accidentally turn it up or down in a tight pocket. Its buttons are sticking out a little, but you can lock them from its user menu. I find them solid, firm to the touch and never wobbling after two weeks of intense use. At 315 grams, it’s on the heavier side, but considering its small dimensions, I find it more portable to its competitors.

Layout & Buttons

Thanks to its small body and clever button layout, I can browse it menu single-handedly, which is a big plus in my book. On top you can spot a volume wheel, on the left side a single micro-SD card slot, on its right side you’ll find On/Off, play/pause, next and previous buttons and all the inputs and outputs were moved to its bottom.

There you’ll find your balanced 4.4mm and single-ended 3.5mm Line-Out – just in case you’re still using portable headphone amplifiers, a USB Type-C sits exactly in the middle used for charging and data transfer and on the right, you have your usual 3.5mm and 4.4mm headphone outputs. 2.5mm jacks can’t be spotted on the latest Hiby devices, but that makes me happy for several reasons (small contact area, higher resistance, low-current delivery, high risk of damage).


From a 1080P 5.5” LCD screen found on their TOTL R8, Hiby went with a smaller 4.97” screen, retaining the same resolution and aspect ratio. Lowering the screen size improved its PPI and sharpness and honestly, this is the highest quality display I’ve seen on any other DAP. It uses an IPS multi-touch panel with great viewing angles, it’s a colorful and high-quality display, with a better contrast ratio compared to say a FiiO M17. Black and white levels are nice, approaching much closer to a flagship smartphone, but it can’t compete with the latest generation displays. Image quality is outstanding thanks to a nice pixel per inch and resolution. On modern smartphones big displays are drawing most battery power and since we are talking about a portable digital audio player, a big screen wasn’t considered, preserving battery life as much as possible. Nonetheless, due to a higher 443 PPI, everything looks crisp and cover albums look vivid and clear.

At this display size, you can certainly do some light gaming on the go and watch YouTube videos, as its newest silicon is more than capable of handling harder tasks…but I would still leave them to your smartphone, so you can have a longer battery life.


From a 4000 mAh battery found on its predecessors as R6 and R6 PRO, Hiby went with a slightly bigger one of 4500 mAh. A bigger battery capacity will need a longer time frame to be fully charged, but thanks to Quick Charge 3.0 standard, you can reduce its charging time with a QC3.0 power adapter. It goes from zero to full charge in about 3 hours and it will offer you back up to ~8.5 Hours of music playback on its regular headphone jack. In real time scenarios, using desktop planar magnetic headphones on high-gain and 4.4mm balanced out, I’ve got around ~6 hours and 45 minutes of non-stop playback, which was enough considering I was squeezing a lot of power. With balanced IEMs on medium gain, I’ve got 7 hours and 20 minutes, as high-gain and a lot of current weren’t needed for ultra-sensitive IEMs.

Hiby added a deep sleep functionality which drifts it off for 25 days, but I couldn’t test those claims. I’m personally turning-off all my devices when not in use (except for desktop DACs and DDC converters), but if deep-sleep is important to you, then RS6 will save battery life for long periods of time.

Under the hood of RS6

The biggest change to its predecessors was moving away from an aging 4-core Snapdragon 425 SoC to a newer and much faster 8-core Snapdragon 660 that runs all cores up to 2.2 GHz. The change is bigger than expected, as sailing through its apps feels snappy, like multitasking on a modern smartphone. Snapdragon 660 is being used by most currently production DAPs and I’m glad that Hiby hopped on board. Hiby moved away from an older version of Android 8.1 to a newer unlocked version of Android 9.0.

Its UI is pretty close to a modern smartphone, it literally moves like one. It boots fast, it turns off instantly and more importantly: it loads apps in split seconds. I can easily multitask with it and going from Hiby Music to Qobuz, Tidal, Roon or Spotify is done in an instant. I can even play DSD files natively and then multitask like a champ, something that R6 and R6 PRO can’t do as smoothly.

As you can expect, RS6 supports Google Play Store, from which you can install any desirable app, including games, streaming apps like Tidal, Spotify, Qobuz and so on, you can install mail clients and anything you’d want really. Qobuz and Tidal worked great for me, I can even listen to my offline music which was great.

Hiby increased the RAM size from 3 GB on R6/R6 PRO to 4 Gb, that helped with multitasking and web-browsing, you can now have multiple apps running in the background without ruining your listening experience. In all fairness, I can’t differentiate my Xiaomi Mi9T PRO from the RS6, they both move and respond to my commands instantly and I’ve never felt a stutter in two weeks of testing. RS6 is providing 64 Gb of ROM memory, out of which ~50 Gb are being offered for music storing and if you would like to expand it, just use a microSD card up to 2 Tb in size.

By far, the most interesting aspect of RS6 is that we’re dealing with an advanced Darwin architecture that is HiBy’s in-house developed digital signal processing architecture. In a breakthrough evolution of traditional R-2R architecture, the system includes resistor ladder linearity compensation and for the first-time advanced features such as linear FIR filters, nonlinear harmonics control, switchable OS/ NOS modes and DSD bypass. The Darwin architecture provides for up to 16x oversampling, with several filter types selectable to preserve linear phase and reproduce the original sound; customizable to fit specific IEMs, ensuring adaptability to different earphones/IEMs of different designs and driver configurations.

When making a high-performance digital to analog converter, the timing of the DAC is the second most important part and this is where RS6 shines bright. Rocking two femto-second crystal oscillators, the timing should be fully preserved, leading to a higher-precision, to a lower jitter (noise) and of course to a purer sound.

Going forward to the amp stage, a discrete current-mode amplification stage is implemented via a single OPA1642 and two OPA1612, supplying abundant current to the output stage. The final power stage consists of four OPA1622 used in parallel for a fully balanced input to output signal path. Its volume is being controlled by a professional NJW1195A digital volume controller for a low channel crosstalk. When it comes to power, RS6 will be providing up to 690mW in 32 Ohms via its balanced output and up to 180mW via its single-ended output. Both line-outs are following the international standard of 2V via SE and 4V via BAL output.

A full-MQA decoder is also on-board. It fully unfolds MQA files (16X mode) not only in Hiby Music app, but also in third party apps like Tidal. As for wireless capabilities, it supports 2.4G and 5G dual-band Wi-Fi, plus all those fancy Bluetooth codecs not only as a sender, but also as a receiver. It can send and receive in the best possible codecs (UAT and LDAC) and thanks to version 5.0, transfer speeds doubled and the distance quadrupled to their former devices (that had version 4.0 or 4.2).

Graphical User Interface (GUI)

I already updated it to the latest FW 1.30G and so far, it didn’t crash on me. Compared to the latest FiiO and Shanling DAPs, Hiby is not providing a dual-boot possibility – one used for off-line music listening only and an Android Mode for everything else. They don’t need any of that, as they developed a Direct Transport Architecture (DTA) that defeats Android’s original sample rate converter, providing a system-wide bit-perfect audio playback. What’s even cooler is that DTA bypasses sample rate conversion of most third-party apps even when using USB audio, achieving a bit-perfect audio output for almost any app. RS6 is running HiBy OS, an in-house developed system architecture that was optimized from the ground up for audio processing. Optimized for Android 9 platform, it opens up the system for free installation of any Android app, on top of that additional features are being provided such as USB audio input and output, wireless audio input and output and system-wide audio effects.

I’m a hardcore Hiby Music user, I’m using it on multiple devices, not only on their DAPs, it was updated multiple times already and plenty of features were being added in the latest updates. I particularly like the Wi-Fi music transfer and Hiby Link – which lets you control your RS6 (that sits in your pocket for example) with the help of your smartphone.

Hiby implemented endless shortcuts, swipes in different directions will access distinct menus, change its volume or other things and I strongly recommend checking its Quick Start Guide if you want to learn them all. You can check if new firmware were released and for convenience, I’m recommended updating it via OTA (Over the Air).

On FW 1.30G, its GUI seems polished enough, it moves fast, I didn’t encounter stutters or slowdowns even when playing 32 bit Hi-Res or DSD content. Streaming MQA files from Tidal and then sending all that to a Bluetooth headphone is simple and intuitive and as much as I’ve tried slowing it down, I couldn’t do that, so no complaints in here.

If you are curious how fast it moves compared to a FiiO M11 Plus and Shanling M8, I’ve ran the latest version of GeekBench on all three and I believe those numbers are speaking for themselves.

Sound Performance

I. Preliminary Sound Impressions

The moment I’ve seen a ladder of R-2R resistors and a powerful FPGA that controls its network of resistors, was the moment I realized that RS6 is a quite a special DAP from multiple points of view. It so happens that the absolute best sounding DACs I’ve tried…are also using R-2R ladders, controlled by state-of-the-art FPGA hardware. Rockna Wavelight DAC ($4950) and Denafrips Terminator Plus ($6500) are still the best sounding DACs I’ve experienced and as you can guess, my curiosity skyrocketed when I found what’s happening under its hood.

RS6 looks like a technical marvel, I mean seriously now, adding tens of resistors, a 256-tap filter, seven op-amps, a speedy CPU, RAM and ROM is such a small body is beyond my imagination. Denafrips Terminator Plus that sits near it weighs 19 Kilos (~42 lbs) and uses a similar tech, with RS6 it’s like looking at the future of high-end portable audio.

Its internal FPGA is so powerful and customizable that…it would be extremely difficult explaining how RS6 is sounding. After engaging its MSEB settings, you can change its tonality from cold to warm, you can alter its bass extension, bass texture, note thickness, vocal performance, you can make your treble softer or sharper, on top of that several plugins are being offered and many others can be downloaded and installed. You can increase or decrease the width of the soundstage that worked like an anti-crossfeed filter, which seriously boosted the left to right soundstage with IEMs. You can use it in over-sampling or native non-oversampling mode, you can use antialiasing filters, you can tune it exactly to your liking, something that I’ve never experienced before.

With competitor DAPs, you’re getting the standard sound signature that can be slightly altered with the help of an equalizer, but with RS6 the customizable sound concept was pushed to the limits. There are several preinstalled presets for TOTL IEMs of 64Audio, Acoustune, Dunu, Fidue, Dita, FAudio, QDC, Softears, Unique Melody and Vision Ears…how cool is that?

For these and other reasons combined, I decided reviewing it in its stock form, without enabling its DPS effects, plugins, MSEB and FIR filters.

The absolute first thing that hit my eardrums was a mesmerizing flow, like musical notes were linked with invisible silk threads, everything poured slowly and naturally towards my ears. There was no grain or listening fatigue, it sat on the opposite pole to a FiiO M11 Plus ESS version. While M11 Plus goes for a higher transparency and for a world-class detail retrieval, RS6 goes for naturalness, for organic textures and for a full-bodied representation. I was surprised that RS6 sounded fast, but also impactful when electronica beats started hammering my ears. The bass output felt spectacular as it was clean & impactful, but also layered and airy, reminding about the sound of good R-2R DACs that I’m using on a daily basis. Its low end was more playful and imposing to said FiiO DAP.

RS6 had an effortlessness in its presentation, it sounded decompressed, a little shy at first when it comes to soundstage, but easy going and unrestrained nonetheless. It reminded a little about the sound of Shanling M8, as RS6 shares plenty of things with that unit. Driving sensitive IEMs via its balanced output was an easy-peasy job, but driving heavy tasks as Meze Elite, Audeze LCD-5 and Kennerton Rognir on high-gain with plenty of headroom remaining on tap, was quite a pleasant surprise. While almost 700mW of power per channel doesn’t sound like a lot of juice…it was nicely controlling the drivers of said headphones and I was far away from reaching its maximum volume levels.

Another highlight was its dynamic range and detail retrieval. Making clean and detailed sounding R-2R ladder DACs is quite difficult. Denafrips Ares 1 and Musician Draco R-2R converters were lacking in that department, delivering enough micro-details, but not as many to impress a hardcore audiophile. RS6 felt clearer, more detailed and it had a higher engagement factor. While Ares 1 was always smooth and relaxing, RS6 could show a different face with aggressive music. I must say that it delivered an engaging performance, as unwillingly I started tapping my feet to the rhythm of the music. Dynamics were quite impressive with all my headphones, but due to a limited power output it didn’t sound as punchy and dynamic as a FiiO M17 or Shanling M8 put on hard-to-drive planars. Still, it walked a similar path, trying to impress with rises and drops of dynamics.

The most important aspect is its tonality/timbre, as it sounds like live music played at a concert. There’s no digitus, there aren’t sharp edges and contours, as RS6 focuses on the innards of the music and not so much on leading edges, so you’ll be getting plenty of meat on the bone, some warmth and a pleasing tonality that will never tire you down. Just before bedtime, I’m connecting a pair of Kennerton Rognir (planar version) to it and I can’t stop from smiling. It’s too addictive, as I’m constantly adding music to my current playlist.

II. Noise Floor & IEM Pairings

Hiby does not specify its exact noise floor in micro-Volts, only a Total Harmonic Distortion of 0.003% is being mentioned and a very low output impedance that sits below 1 Ohm, meaning that I will be testing its noise floor the hard way, with the help of several ultra-sensitive IEMs.

Since high-gain and 4.4mm are delivering the highest power output and subsequently the highest noise output, I went directly on the balanced output, I’ve paused my music and went all the way up with a pair of FiiO FA9, just to discover the sound of silence. The 3.5mm jack performed identically and regardless of the volume position, RS6 was completely noiseless. I redid my tests with third party apps like Qobuz and Tidal and sure enough, RS6 was again inaudible as far as noise goes, sounding as if it was turned off completely. There was a complete silence in between passages and all I’ve heard was a pitch-black background with musical notes appearing out of thin air.

Dynamics were swinging in full-force, music was hitting me hard, with a huge grin on my face everything felt at its right place. Even going as loud as 70 out of 100 on its volume, everything remained clean and defined, without losing inner detail or crispness. In this regard, it behaves exactly as a high-end DAP, so no complaints in here.

Since FiiO FA9 is currently my noise sniffers due to their high sensitivity of 113dB per a single mW of power, everything else like FiiO FH9, Meze RAI Penta, 7Hz Timeless, Little Dot CuKIS and Kinera Skuld performed absolutely the same. Wiping out noise out of existence, channel separation increases and the feeling of air traveling around my tunes improved as well, boosting inner-details, for a higher engagement factor. This story repeated itself with desktop headphones, even the highest sensitivity ones like Apos Caspian couldn’t detect traces of hiss or hum, proving that we’re dealing with an amazing piece of engineering.

Stacking it with my smartphone and using it as a USB DAC, should be the ultimate test, as it needs to deal with Wi-Fi, Bluetooth and 5G interference, but I’m happy to report that it sounded exactly as it did on its own, it didn’t increase the noise floor at all, making it a perfect portable DAP or DAC to be used on the go or at home.

III. Power Output

RS6 offers almost ~700 mW in 32 Ohms on its balanced output and while that might not sound like a lot, it was more than enough for a flock of dynamic headphones and planar-magnetic ones. Throwing portable over-ears at it, IEMs and even several desktop dynamic headphones didn’t pose a slightest problem for the little Hiby, as it easily drove them with flying colors. Engaging high-gain on its balanced output, I could go up to 65 out of 100 with the Kennerton Vali, Erzetich Mania and Apos Caspian. Kennerton Gjallarhorn and M12S needed even less power, leaving plenty of headroom for higher dynamic range tracks.

Moving up the ladder to something more interesting like planar-magnetic headphones, Kennerton Rognir, Erzetich Phobos V2021 and Meze Elite were already loud enough at around 70 and maximum I could go was 75, again leaving tons of headroom for crazy dynamic swings. All those headphones were nicely controlled, delivering an organic midrange, a powerful kick with bass intensive music and a harsh-free top octave. Dynamics were swinging in full force, offering a high engagement factor and a good transient response. I was expecting this, as FiiO’s M11 Plus performed more or less the same, with a small difference that RS6 was a more alive and engaging sounding.

Only when I switched to the Audeze LCD-4, I felt that dynamics were slashed by a little, volume wise I was going past its 80-volume level, remaining a lower headroom on tap. On higher quality recordings as classical and blues, often times I was close to maximum volume and LCD-4 weren’t singing the way I like it. It was clear to me that LCD-4 needed more power to shine and this shouldn’t come as a surprise to anyone. In the case of LCD-4, only high-powered DAPs as Shanling M8 and FiiO M17 were doing them justice, driving them close to what I would describe as perfect. Hifiman Susvara didn’t perform well even at maximum power, but considering its diminutive size and the fact that pocketable DAPs weren’t made for hard to drive planar-magnetics, RS6 performed above my expectations.

IV. Soundstage & Depth

Soundstage, imaging and depth are always tied to how powerful the output stage really is and that’s one of the reasons I recommend using its 4.4mm balanced output for the best results. If you look closer at its specs, you’ll observe a substantial difference in terms of channel crosstalk (98 dB via balanced and 72 dB via single-ended), again suggesting that RS6 would sound considerably wider on all axes via its balanced output.

Zooming out for just a minute, if you’re hunting for a big sounding desktop D/A converter that would be placing the sounds all around you, creating a breathable type of sound, then nothing beats well designed FPGA and R-2R units.

By definition, R-2R units are sounding expansive, layered and quite airy and the same can be said about the sound of RS6. Even if FiiO’s M11 Plus is a little bigger and offers slightly more power on tap (via SE output), Hiby’s RS6 took the lead, delivering a bigger stage, expanding it in all directions, especially with open-back headphones. While M11 Plus was precise when it comes to imaging and positioning of the notes around my head, RS6 pushed everything a little further, as if I was looking at a bigger picture. On top of this, Hiby puts at our disposal several DSP presets and plugins that could stretch the soundstage even wider. For example, Atmosphere Enhanced adds some depth and layering to crowded music and Sound Field plugin seriously boosts the left to right soundstage, so much so that some of my headphones are almost unrecognizable if I’m enabling that plugin. The good part is that you can tune those plugins to your liking, you can tune the width of the sound field to better match your headphones. With semi-open headphones a width of 1.5 worked best and with fully open-back headphones a width of 1.2 – 1.3 was more to my liking.

What was clear from the start, is that even without engaging its hardware-based DSP, it was never bi-dimensional or up-front sounding, on the contrary, RS6 was challenging bigger and more expensive units that had more power on tap. After two weeks of burn-in, it started moving more air around my head, adding some heft and increasing the feeling of a breathable, three-dimensional sound. Even with tiny IEMs as FiiO FH9, music flew far and wide and crowded tracks were no longer closed-in and personal, decompressing them on all axes. It was expressive and quite emotional too, fully surrounding the listener, so much so that I’ve forgotten that I was using IEMs in the first place.

Beryl by Mark Knopfler (Qobuz / Tidal) is such a well-mastered track, it almost feels like a live record on nicer desktop or portable setups. RS6 together with FH9 felt limitless as far as soundstage goes. I just closed my eyes and completely immersed myself into it. The whole track felt punchy and alive, guitar plucks felt playful and well controlled, gently rolling-off the top octave as I was never bothered by the treble output. There was a nice sparkle in the air, harmonics felt warm and inviting, leading towards a relaxed presentation. The scale of this track really shows off RS6’s impressive soundstaging capabilities.

V. Transient Response

When I just received it, I was dismayed as something didn’t sound right to me. Music was pressing the brakes and the low-end was nowhere to be found. I’ve immediately remembered that R-2R units that passed through my hands sounded exactly like that in the first week. Tens of resistors that are converting zeroes and ones into analog signals need some time to settle down and enter their normal parameters, so I’ve connected a power adapter to it and let it play for a few days on repeat. Several days later, the tiny RS6 didn’t resemble my impressions, as finally bass notes appeared in my tracks and I no longer felt boring and subdued dynamics. I’m not exactly sure when everything clicked into place, but right now after about two weeks of music playback, I can no longer complain about slow transients and limited dynamics.

Dynamics is a key word with RS6, as its low end stays head and shoulders above the rest of the frequency response. A complete 180 degree turn to my first impressions and that makes me happy, as this part is extremely important to me. I’m reminding that I’m using it in its stock form, but as usual, you can make its low-end even fuller, faster or drier if you will, sky and your imagination is really the limit with RS6.

I must confess that I spent a lot more time with desktop planars on it, as Meze Elite together with Kennerton Rognir (planar version) sounding above my expectations. I’ve got speed with electronica music, fast decays and instant rises of dynamics. The tiny RS6 could deliver great punches down low, in this regard it seriously outclassed a FiiO M11 Plus and Shanling M6 V.21. It delivered a great rumble down low and, in my view, RS6 fully preserved the dynamic range and never limited the transient response. Considering its diminutive size, I can’t ask for more. Driving heavy duty planars AND delivering a punchy low-end, with instant decays is all I could possibly desire. There were better sounding DAPs in this department, but certainly not at this price point, making RS6 a worthy contender for a Do-It-All DAP below the $1.5K price.

While on the surface Terracentric by Rodrigo y Gabriela (Qobuz / Tidal) looks like a simple acoustic track performed by two marvelous human beings. My blood immediately started boiling as the tempo increased its pace. Could you toe tap and headbang on mere acoustic guitars? On the right setup, of course you can and I’m glad that RS6 wasn’t limiting dynamics and the final impact. Rognir sounded as if I connected them to a desktop setup, punching with a serious force and keeping up with a fast tempo. RS6 brought the thunder and put a smile on my face, a clear sign that transients and RS6 are strengthening their ties.

VI. Detail Retrieval

If you research a little about R-2R DACs, you’ll understand that no matter how precise those resistors are, they will be slightly lowering the resolution and dynamic range. A powerful FPGA can come to the rescue, re-clock and reconstruct the signal and that’s exactly what RS6 is doing by default. While…it can’t challenge the cleanest sounding DAPs out there, I believe that FiiO M17 still holds that title, RS6 was still clean and noiseless at all times. There’s an interesting phenomenon with RS6, no matter how hard you try, the leading edges/the contours of the notes were never forced or overly-sharp sounding to me. For example, M17 can sometimes sound too defined, too sharp and too clean, almost robotic – suggesting that a digital to analog conversion in happening in real time, while with RS6 it’s like being at a live concert and having a blast in the company of your friends. You can feel the plucks, the brass is tingling your stomach and the snare drums are landing some precise hits on ear drums loud and yet, everything is delivered in an organic and natural way. RS6 isn’t highlighting micro-details, it never moves the spotlight toward the smallest nuances, as it wants to conquer your heart with its natural timbre. Its tonality is outstanding, unlike many other DAPs that passed through my hands. To a certain degree is reminds me about the sound of Rockna Wavelight and Denafrips Terminator Plus that are also putting a higher accent on macro-dynamics, on the innards of the music, on its density and texture. While guitars aren’t extremely sharp, you can feel their plucks vibrating in a natural way, it’s complicated describing the feeling with mere words, but it does sound like a digital vinyl.

The percussion work on The Q Sessions by Christian McBride (Qobuz / Tidal) felt exemplary, standing out immediately with its naturalness and texture, never becoming burdensome or out of place. The cello and bass guitar added a nice extension in the lower frequencies, improving the layering and moving plenty of air down low. This track really highlights how expressive RS6 can be with macro-dynamics. Its clarity and natural harmonics had an emotional impact on me, as most entry to mid-level DAPs were seriously lacking in terms of dynamic range, almost sterilizing the whole listening experience. With the right headphones and selection of music, RS6 could offer an out-of-body experience, letting the sound take over not just audibly but emotionally as well.

VII. Frequency Response

Hiby’s latest DAP covers the full frequency response spectrum even if several parts of its FR are standing out more often. Apart from that, you’ll still hear everything from the lowest pits of sub-bass to the highest treble peaks.

A. Bass

As I’ve mentioned before, its low-end felt lackluster in the first days, blooming beautifully a few days later, adding weight, punch and a lot of substance down low. RS6 is one of those DAPs that will immediately win you over with its weighty bass performance, even starting with the lowest octaves as 20 Hz. It can easily sustain longer bass notes and deliver them with a higher sound pressure level. I must say that it reminds me about the sound of Shanling M8, as RS6 moves higher quantities of air down low, giving an impression of a powerful bass performance that could was felt with the entirety of my body. Mid-bass was exactly as impressive, maybe by a hair more, always attracting my full attention to it. It felt elevated by a hair, adding warmth and a higher saturation in this region. RS6 is not the fastest sounding DAP out there, but it still delivers a clean and impactful bass performance. Forget about distortions even at maximum volume, as harder loads as Audeze LCD-4 didn’t send it into clipping territory, highlighting that I’m dealing with an excellent bass performance.

B. Midrange

While I didn’t feel an overly smooth or all over the place midrange, it always felt natural and velvety sounding to me and I wouldn’t expect anything less from an R-2R ladder of resistors that uses some of the warmest sounding OPA op-amps in the business. From a decent amount of DAPs I’ve tested as of late, I believe RS6 doesn’t have a fierce competition in here, providing a juicy and natural midrange across the board. Those guitar strings carried more emotions, vocal performance was to die for, this is definitely a soul-grabbing midrange that highlights texture and inner details more than anything else. Leading edges are not the sharpest, in return we’re getting a life-like midrange rendition that goes towards warmth and smoothness. Yes, it’s by a hair elevated, but man…it worked exceptionally well with instrumental and acoustic music and don’t get me started with lifeless or linear sounding headphones, as it will be infusing some of its own medicine, adding warmth and a higher engagement factor. In the end I’ve got a full-bodied, weighty and distortion-free midrange and that’s everything you need to know about this region.

C. Treble

Its treble performance does remind me about the sound of non-oversampling DACs, of R2R DACs and sometimes of FPGA software defined DACs. There’s just an easiness and a harsh-free presentation that is missing on other DAPs. You can feel the brass of cymbals, you can feel a higher impact of snare drum hits, but you’ll never feel the fake ringing associated with those instruments. There’s texture, there’s detail and transparency, but sharpness is missing the action and that’s another trait I find interesting and unique with RS6. You know, I’m very much into all kinds of music, including treble-intensive tunes and with some particular gear, I just refuse listening to such genres, as I won’t enjoy my time. With RS6, I could listen to rock all day long, feeling metallic textures, sans the issues associated with less than perfect digital sources. I can’t call it rolled-off in here, there is plenty of presence and detail, it’s not overdone and it’s not attracting a lot of attention to it. This is an outstanding treble performance that I wish I could borrow and place it in some other DAPs.

VIII. Wireless Performance

Hiby finally embraced the latest Qualcomm Bluetooth chipsets that are providing a much wider codec support and BT version 5.0 will deliver a wider and stronger coverage and let’s be honest…when it comes to Bluetooth, Qualcomm are doing the best chipsets full stop. RS6 is Bluetooth 5.0 enabled and it supports all those fancy Bluetooth codecs, as UAT and LDAC.

As a sender, I connected a FiiO UTWS3 to it, driving several pairs of IEMs. The pairing process was easy and straightforward, its BT connection was stable and reliable and all IEMs sounded good to almost great via Bluetooth. With a DAP of this caliber, I would stick to wired headphones for a much better performance, but in a gym where sound quality doesn’t matter as much, I could see myself using this feature quite often with UTWS3.

As a receiver, I’ve connected my smartphone to it, I used Qobuz and sent all that goodness to RS6. The pairing process felt easy-peasy and BT connection was rock solid even at 15 meters away in an open space. I personally don’t understand why would you use it as a Bluetooth receiver, as you can use any streaming app directly from it and it really moves as a flagship smartphone, you can even use your NAS, DLNA and UPnP servers and those will sound by orders of magnitude better than any Bluetooth codec. But hey, additional features never hurt, it’s always cool to have them around.

My Conclusion

I never believed I could take with me a Denafrips Terminator Plus or a Rockna Wavelight in long or short trips, but I guess I was wrong. Hiby’s RS6 borrows a lot of technology from said D/A converters, choosing a higher engagement factor, flow and natural textures above anything else. If there’s a DAP that tries to elevate your mood and cover your body with goose bumps, then Hiby’s RS6 is definitely that one. In my case it felt and performed like a high-end DAP with IEMs and headphones alike. Its build quality felt top-notch, that full copper case always begs to be admired and I really like its minimalist layout and handsome look. It’s impossible disliking its unique sound character, its hardware presets, plugins and sound enhancements. Put two RS6 near each other with different sound enhancements enabled and they will sound at poles apart and I find that extremely appealing. I hope that Hiby will further expand and improve its RS line-up as I want more or that meaty bass, smooth midrange and harsh-free treble.

RS6 performed above my expectations with every IEM and headphone I had at my disposal, there isn’t a more customizable DAP today and that’s why I’m going to award it with our prestigious Gold Award. Congratulations to the team and I’m looking forward to what’s coming next!

Hiby RS6 will cost you $1399, but considering all of the above, I truly believe its price point was fully justified.

Hiby RS6 was kindly provided by Hiby Music and you can get it directly from their Online Store. In case you’ll get one, please come back and leave a comment below. I’m curious to know how it performs with your IEM and headphone collection.


  • Solid as a brick, top notch build quality
  • Its CNC machined copper case started growing on me
  • That leather case looks and feels premium
  • Probably the nicest LCD screen I’ve seen on a DAP
  • A newer System-on-Chip and a bigger RAM size made it way faster and snappier
  • Unlocked Android 9 with Google Play Store support
  • Modern and fast-moving UI, Hiby Music never looked better
  • Excellent selection of presets, plugins and DSP effects. If you like customizing your sound, then RS6 is definitely for you
  • Warm tonality, going towards easiness and naturalness
  • There’s a good rumble down low, punches above its weight
  • Saturated midrange delivery
  • Harsh-free top octave, zero listening fatigue
  • Deep and spacious sounding at all times
  • Dead-silent with IEMs even on high-gain
  • Offers a wide Bluetooth coverage and codec support
  • There’s plenty of power even for demanding planar-magnetic headphones


  • Transient speed could be improved in the future
  • A bit on the heavier side


  • DACs: Denafrips Terminator Plus, Rockna Wavelight, Audiobyte HydraVox & HydraZap, Gold Note DS-10 Plus & PSU-10 EVO, SMSL VMV D2, Singxer SDA-6 PRO, Gustard X18
  • DAPs: Hiby RS6, FiiO M17, M11 Plus ESS, Shanling M8
  • Headphone Amps: Ferrum OOR + Hypsos, Flux Labs Acoustic Volot, Enleum AMP-23R, Burson Audio Soloist GT, Trafomatic Primavera, several Topping, SMSL & Gustard units
  • Preamps: Musician Monoceros, Benchmark HPA4, Topping PRE90
  • Power Amps: KECES S300, Benchmark AHB2 (x2), SMSL SA400, Burson Timekeeper 3i
  • IEMs: FiiO FH9, FH7, FA9, FA7S, FD7, Meze Rai Penta, LittleDot Cu KIS, Kinera Skuld, 7Hz Timeless & others
  • Portable headphones: Sony WH1000-XM4, Sennheiser Momentum 2, Meze 99 Classics
  • Full-sized headphones: Hifiman Susvara, HE1000SE, Arya Stealth, Sundara, Audeze LCD-5, LCD-4, Erzetich Phobos V2021, Phobos V2018, Erzetich Mania, Kennerton Rognir, Magni, Gjallarhorn, Vali, M12S, Apos Caspian, Sendy Peacock, Apollo, Aiva & others
  • Loudspeakers: KEF Reference 3, Sound Of Eden Crescendo UNO
  • Interconnects: QED Reference (x2), Topping TCX1 (x2)
  • Speaker cables: Kimber PR8, Audioquest Type4
  • Power Cables: Isotek EVO3 Premier (x3), iFi Audio SupaNova (x2)
  • Balanced Isolation Power Conditioners: PLiXiR Elite BAC1500 (stereo setup), Elite BAC400 (headphone setup)

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