The product was provided to me free of charge for the review purpose in exchange for my honest opinion. The review was originally posted on my
blog, and now I would like to share it with my readers on Head-fi.
Manufacturer website:
Hiby.
Intro.
It probably sounds cliché, but you have to be living under a rock if you never heard of Hiby. Maybe not as well known yet for their hardware, Hiby has been behind many DAP releases (FiiO, Cayin, Shanling, Hidizs, Questyle, and others) with their custom firmware, as well as their own popular music app for smartphones. And thanks to their Android OS software workaround, many of these DAPs are free of Sample Rate Conversion (SRC) limitation which down-samples the audio. I guess it was only a matter of time before they decided to release their own DAP – Hiby R6. Considering the accumulated experience while working with other DAP manufacturers, Hiby did their homework to come up with an impressive hardware spec to boost the Android performance, something you would expect from higher end smartphones.
In their debut release, Hiby decided to introduce R6 DAP through Indiegogo crowdfunding campaign, giving the project more exposure with a help of social media. The campaign was successful, over 575% funded, but a real surprise came later when they announced the shipment of the first batch of aluminum alloy R6 ahead of the proposed schedule - very rare for any crowdfunding campaign. Of course, nothing is perfect, and Hiby design decision of high output impedance did raise questions in audiophile community. But I found it to be not the end of the world, if you got iEMatch handy, and I will go into more details when discussing R6 pair up with numerous headphones in corresponding section of my write up. Now, let’s proceed to the review.
Unboxing and Accessories.
Here, unboxing was straight forward, with a basic black compact sturdy box, and R6 under the cover in a secure foam cutout. All the included accessories and documentation was underneath, found at the bottom of the box once you take the foam tray out. The back of the box had detailed highlights of the features with a graphic thumbnail illustration of each one.
The included accessories are basic, yet useful. You get "Hiby" branded usb-c charging/data cable (decent quality), and line out coax cable to connect digital output to external DAC/amp coax input (longer cable with a durable shielding). 3.5mm to 3.5mm line out audio cable was not included, though would have been appropriate here. You also get extra high-res stickers and a screen protector, while a pair on the front and the back has been already applied to R6. Plus, included is a pin-tool required to open the concealed uSD door to take out the tray with a flash card.
As part of Indiegogo stretch goals, a silicone case and tempered glass screen protector were also included. Silicone case is basic cheap case with covered buttons. It's actually not bad to enhance the grip and provide friction when placed on the surface, but it's not as "glamorous" as a leather case. Tempered glass has an advantage over a regular protection film in case if you have a direct impact which absorbs the shock, shattering only the tempered glass instead of the display.
The leather case is optional and cost $24 when ordered from IGG page. It has a dark blue color which from a distance almost looks black, and made of full-grain leather with felt inner lining to protect R6 metal finish from scratches. It has a slide-in design from the top, keeping the top fully open, and has generous cutouts around the buttons on both sides to allow direct access while keeping buttons recessed and safe from accidental pressing. It also has a generous opening at the bottom for usb-c port access. I like this case.
I was also told that MITER is working on a case for R6, and I will update the review once I get my hands on a sample. Traditionally, MITER cases use a soft leather and feature their signature kickstand to allow propping R6 up when watching video/movies.
But, the #1 Recommended accessory for R6 is iFi Audio iEMatch, a very compact durable pigtail dongle which reduces the output impedance and nearly eliminates the issue of R6 high OI. It’s available in 3.5mm and 2.5mm variants, where you can also get a cut-down 3.5mm Ear Buddy version with a similar functionality.
Design.
To make their DAP pocket friendly, Hiby kept design very straight forward and slick. You have a typical "smartphone" rectangular bar shape, 116 x 66 x 15 mm in size with 190g (aluminum alloy) or 275g (stainless steel) in weight, and 4.2" touch screen display occupying the front and glass panel on the back. While all the internal design/components are the same, you have a choice of either aluminum alloy or stainless steel (316L high-impact) chassis. Unlike some other DAPs, Hiby doesn't claim any sound difference between these two.
While the general shape of the DAP is rectangular, the top and the bottom has this slight recessed arc shape to give it a more unique look. The sides have a little rounded shape for a more comfortable grip, though I still prefer to keep it in the case to make it less slippery, especially with a glass back. Using a case enhances the grip and prevents it from sliding across a flat surface.
Left upper side of the DAP has Volume up/down (+/-) nice concave-in buttons with a tactile response. Keep in mind, once you press the button to change the volume, you also get on-screen volume touch control which you can slide up/down for a faster adjustment. Toward the lower corner of the left side, you have a concealed micro-SD card slot which opens with an included accessory pin. It's a small tray which is flush with chassis, keeping the card secure and dust free, similar to smartphone mechanism.
Right side has Power button at the top with a multi-color LED which indicates charging, playback, and different types of playback hi-res formats. Below it is 3 playback control buttons with a larger Play/Pause in the middle and smaller Skip Next/Previous above and below it. All the buttons have concave-in shape, etched with a corresponding functionality (except for Power button), rattle free, and have a very tactile click response. I like how they vary in size for an easier ID as you slide your finger, and I also appreciate the ergonomics of asymmetrical layout.
The bottom of R6 has usb-c port which becoming more popular with DAPs and allows high speed/current QC charging and faster data transfer. Plus, this port is used not only for charging, but also data transfer, USB DAC input functionality, and Digital Output transport control. The top of R6 has 3.5mm port which doubles as Line Out (LO) and Coax outputs (selected from audio settings menu). Next to it you have 3.5mm single ended (SE) headphone output and 2.5mm balanced (BAL) headphone output. Btw, I didn't find any screws accessible from the surface.
Under the hood.
As I mentioned in the intro, Hiby did their homework and picked top performance components. To ensure the Android 6.0 OS runs smoothly, Hiby stepped it up with Snapdragon 425 SoC Processor and 3GB of DDR3 RAM. While some other DAPs use 1GB RAM just to make sure you can run a streaming app, or 2GB of RAM to be able to run other apps, 3GB of RAM doesn't just enable you to run all apps, but to run it as efficient and as responsive like you would have with your smartphone. Internal storage is limited to 32GB, that's a pity, but you have uSD expansion to support the latest max capacity card. Plus, wifi streaming and LAN support expands the playback variety.
Audio processing is under control of dual ESS ES9028Q2M DAC, SoundPlus OPA1612 audio opamp (2x used as Low Pass filter), and TPA6120a (2x hi-fi stereo headphone amp) driving both single ended 3.5mm HO (120mW @ 32ohm, 118dB SNR) and balanced 2.5mm HO (300mW @ 32ohm, 120dB SNR). That's quite an impressive and powerful spec, though output impedance here is on a high side at 10 ohms. With a spec like this, you can play majority of hi-res lossless formats, such as FLAC, APE, WMA, WAV, ALAC, Apple LOSSLESS, DSF, DSDIFF where you have native support/decoding of DSD 128/256 and PCM up to 32bit/384kHz, as well as support of ISO DSD. Plus, support of lossy formats, such as MP3, AAC, WMA, OGG. Keep in mind, Hiby mentions to be able to bypass Android sample-rate conversion to ensure bit-perfect output from any app.
Its 4.2-inch touch screen IPS display is high-density 300 dpi, with an impressive resolution of 768x1280, supporting 16 million colors, and wide viewing angle. I know, these are just spec numbers, but when you look at the display, especially that color-splash wallpaper with its deep/rich colors, you will understand and appreciate the meaning of this spec. Furthermore, for a wireless connection, you have dual-band (2.4G and 5G) WiFi radio, and Bluetooth 4.x with aptX codec support.
The provided battery has 4000 mAh capacity and supports quick charging (QC 3.0) standard (140min to full charge), where you can use either DC 5V/2.5A or 9V/1.5A. While Hiby mentioned about 12hrs battery life which is impressive for high performance touch screen Android DAP, I actually found this number to be a little on a conservative side where in my best- case scenario I was able to get even more out of battery.
Before timing the battery performance, I let R6 run a few charge/discharge cycles to make sure battery is fully calibrated. I started with U18t and single ended cable, low gain, playing MP3 (320kbps, 44.1k/16bit) in a loop at a reasonable volume level with a display off, only occasionally turning it on to check the battery percentage. During this test, I got
12.5 hours of play time with 3% battery juice remaining. Later, I realized that I never turned the WiFi off, which I’m sure contributed to additional battery drain, thus making me believe that a best-case scenario would have been closer to 13hrs of total playback time.
Next, I switched to CFA Vega with a balanced cable, in high gain, WiFi radio on, pushing volume higher to drive these lower sensitivity IEMs harder while playing hi-res FLAC file in a loop. The result was
7hrs and 45min of playback time. Still not bad for this relatively worst-case scenario, though I’m sure with DSD files it would have been even lower, as expected. Btw, having LED indicator built into a Power button is quite convenient to get “visual” confirmation if you are playing a hi-res file without turning the DAP on.
Wired and wireless connections.
Thanks to a dedicated LO/Coax and multi-functional digital usb-c port, Hiby R6 has flexibility of many various wired connections to enable its use as a transport or to pair up with an external dac/amp. Here are some of the examples of my testing.
R6 vs R6/HA-2 – Using Shanling usb-c to micro-usb interconnect digital cable, I seamlessly paired up R6 with Oppo HA-2 portable dac/amp, using it as a digital transport. In comparison to a direct R6 connection, I found the sound with HA-2 to have a little more bass impact, but other than that it was very similar. Also, with external connection, your HO impedance changes according to the spec of a paired up device.
Micro iDSD BL – While trying to stay portable using DAPs, Micro iDSD is one of the few transportable DAC/amp exceptions I still use due to its sound quality and flexibility supporting various connections. Using a budget eBay digital cable with usb-c to full size usb, I had no issues connecting to iDSD and found the sound to be very clear and detailed with a punchy bass.
In comparison, I switched to use Coax output of R6 (needs to be selected in audio settings from pull down menu), where in this pair up I found the sound to be a little smoother and with a noisier background in comparison to digital connection above.
R6 vs R6/E12A – To take advantage of R6 dual DACs while bypassing its internal amp section, I switched to LO (the same menu option where I selected SPDIF above) to test R6 with FiiO E12A portable amp (my neutral amp reference) where I found the sound to be a little bit smoother and the background not as dark. Based on what I’m hearing, it sounds like R6 amps have a blacker background and a brighter tonality, leading to a more resolving sound.
While I’m not a big fan of using portable DAP as USB DAC, this “wired” feature is available with R6 and convenient on the go when you are traveling with your laptop and want to enhance the sound of its stock chipset. Here, after installing Hiby provided drivers, my Win7 laptop recognized R6 without a problem, connected as usb DAC, and it even displayed the sampling/bit rate of the song. The sound quality was the same as listening to R6 standalone.
For Wireless Bluetooth test, I used Sennheiser Momentum Over-ear wireless and B&W P7 Wireless full-size headphones. I tested their performance paired up with R6 vs my aging Note 4, though in both cases it should support aptX codec. I found that I could push headphone volume louder with R6 in comparison to my Note 4, not sure if there is some volume limitation for safety reason with my phone.
In more details, Senns Momentum are picky in some pair ups, but I found no issues with R6. I was able to walk across 50ft of open space, before the sound started to cut off. Comparing the performance of R6 vs Note 4, it sounded nearly identical, crisp, revealing, and with an articulate bass. With P7W, the transmission was clear across 55ft of open space, the sound was balanced and I enjoyed P7W deep bass impact. As a matter of fact, I’m hearing an even deeper sub-bass rumble when paired up with R6 over Note 4.
No wireless discussion could be complete without WiFi and Streaming performance. I had R6 connected to my ASUS RT-N66R router (oldy but goody), 5GHz band. While I was streaming Spotify, had R6 aluminum in a leather case placed in the front pocket of my shorts. Walked to the other end of the 1st floor, an open space of a little over 60ft, and had no issues with streaming, though I was down to 1 bar.
In general, I found R6 to perform like a decent smartphone (not exactly the latest TOTL, but an average smartphone), and with Google Play pre-installed you have access to many different apps, including streaming. I don’t stream too much using apps or from in-house server, but occasionally use either Spotify or DI.fm apps. I know many asked me about Tidal, but unfortunately, I have no account thus wasn’t able to test it. I’m aware that Hiby is working directly with Tidal to fix some minor compatibility issue and hopefully will be able to resolve it soon.
GUI.
While many Android DAPs feature a common interface found in smartphones and tablets, not many of them perform on the same level when it comes to GUI response and app compatibility. Here, thanks to Snapdragon 425 SoC and 3GB of DDR3 RAM, playing music, browsing internet, or streaming audio is a breeze. Plus, Google Play Store already pre-installed so you can start downloading apps without a need to side-load apks or installing custom ROMs.
Interestingly enough, while Notification bar has a familiar volume icon with a volume level, Bluetooth icon (when enabled), WiFi icon (when it's on), battery icon with remaining %, and a time, once you pull Notification bar down, unlike some other DAPs, you will find a very minimalistic set of short-cut controls: down to brightness adjustment, WiFi and Bluetooth controls, and Audio Settings. There is no general Android Settings icon, instead it's a separate shortcut on the main Android screen, also found in apps drawer.
Under Audio Settings in Notification menu, you will find Low Pass filter selection for ESS DACs which includes: Minimum phase, fast roll-off, and slow roll-off options; Multifunction Output selection between Lineout or SPDIF; Gain with Low and High settings; L/R channel balance slider; and Tonality (harmonics) selection of Reference, Warm, and Tube Amp. The Settings shortcut on the main screen takes you to a regular Android settings section with typical system settings of WLAN, Bluetooth, Data usage, Display, Apps, Storage, Battery, and others. Perhaps Hiby wanted to keep Notification bar less crowded, but I would have love to see Settings shortcut in the upper right corner where it could be accessible from any screen, instead of searching for the shortcut on the main Android screen.
Of course, you are free to run any audio app of your choice which going to have its own custom GUI, but since we are on a subject of Hiby DAP which comes already with its Premium Hiby Music v3 app, I didn't bother to use anything else, especially after I learned of MageSound 8-ball DSP effects. Hiby Music app is very user friendly and feature-rich, and its navigation on R6 is very fast, especially since its interface is very logical to navigate.
The main screen at the start has top bar with Music listing where you can navigate by a song Title with the ability to play all in Shuffle mode or to select individual tracks to add to Queue or to Playlist or to Delete. You can also navigate by Folder or sort by Album, Artist, Genre (depending on ID tag of your songs), or Private Cloud (DLNA/LAN or Baidu?). There is a separate tab for Favorites, Recently played, or Playlist. Also, there is an option to enable HibyLink to connect to your smartphone. Last, but not least, a Search menu. While going through these choices above, at the bottom you always have a visible playback bar with a currently selected song with navigation controls.
Tapping on that playback bar brings up the main playback screen, also with a clear layout. At the top you see a song/artist name with 3-dot setting menu next to it (add to playlist, share, EQ, show album info, and properties display). Below it, the top half of the display shows embedded artwork (if available), and you can swipe to the left to see if there is embedded lyrics, and one more swipe for a detailed info about the song. And speaking of detailed info, once playback starts, the sampling rate of the song is displayed in the notification bar, something I haven't seen with any other DAP yet.
In the lower left corner of artwork screen, you can tap to select playback mode: loop all, loop one, straight play through, or random playback. The lower right corner has a link to open current playback queue, based on either a folder where you are playing from or an album or playlist. Lower part of the screen has playback controls with Skip Next/Prev on the sides, and a large circle with Play/Pause in the middle and Fast Forward/Back navigation to scrub through the song. While I personally prefer a straight horizontal bar to touch-forward through the song, this Circle navigation bar became a signature control of Hiby app, and it's large enough for a precise control.
Also, I liked the EQ interface which you can access from the playback screen. First of all, unlike many other DAPs where enabling EQ drops the output by at least 3dB to avoid clipping, here the volume doesn't change but you have +/-12dB amp gain adjustment. Then, you have 10-band EQ (31,62,125,250,500,1k,2k,4k,8k,16k) with each band having +/-12dB adjustment. These 10 bands sliders spread across 2 screens, but the top of the EQ has a common graphics screen with a visual of all 10 bands so you can see the final EQ curve. Furthermore, in addition to a custom preset, you also have 8 genre specific EQ presets which you can modify further.
Hiby Music app comes with its own comprehensive Settings menu which can be accessed by swiping to the right from the main screen of the app. Here you can access Music Scan (scanning all or specific folder, with a number of scan options), Download manager (assuming, for songs?), Equalizer (as described above), MageSound 8-ball (Hiby own special effects), Plugin (available plug ins, currently with Parametric EQ and Joe's Sound Filed Enhancement plugin), Sleep timer, Settings (a very comprehensive set of music app settings), Quick guide, and About section.
I'm sure more plugins will be available soon, and I hope PEQ will get its own GUI since for now it's very low level basic interface. MageSound 8-ball is what many will be interested in. It’s a very comprehensive set of very useful effects that can really shape the sound with quite natural results. You can adjust the "temperature" by going from cooler/brighter to warmer/darker signature, adjust bass extension (from light to deep), bass texture (from fast to thumpy), note thickness (from crisp to thick), vocals (from recessed/crisp to more forward/smoother), female overtone, LF/HF sibilance level, impulse response (from slow/music to fast/hard) and level of air. At first, I assumed it will be more like an EQ adjustment, but the more you use it, the more you realize it's like DSP effect processing, reminding me of BBE/JetEffect in some way.
Bottom line, no matter what app I was using, everything was very responsive and super fast.
Sound analysis.
Usually, I like to get at least 100hrs of playback before any DAP sound evaluation, so after I received R6, it spent a week on a burn in, just playing random music in the loop while I switched between SE and BAL, making sure HO were loaded. As my usual disclaimer, DAP sound description is very tricky because you are describing the synergy of the DAP with headphones you are listening to. It’s easy to fall in a trap of describing the headphone signature, thus I usually go through a number of headphones, from neutral to more revealing, to find common sound characteristics relative to the source, rather than headphones.
In general, I found R6 to be a neutral DAP with a little tilt toward a brighter more revealing side. It has a rather wide soundstage expansion, both in width and in depth. It also stands out with decent dynamics, where, regardless of headphone pair up, the sound was always vertically expanded, never felt compressed. The background is black and hiss free even with most sensitive low impedance iems. Also, the transient response of notes on/off transition is clean and sharp, which makes details pop out faster. Though in the settings there is Tonality selection with Reference/Warm/Tube amp, all three sounded on a reference level to me. MageSound 8-Ball effect is where I was able to tweak tonality with a more noticeable effect. And, especially when paired up with more revealing analytical earphones/headphones, you can appreciate the level of layering, transparency, and separation between the sounds.
But there is one variable when it comes to a tonality since R6 has a higher than usual output impedance, 10 ohms, while today's typical DAPs have around 1 ohm or less. So, what does that mean? With majority of full size dynamic driver headphones and single driver IEMs or higher impedance headphones/iems, a pair up with R6 will have a minimum effect on a change of the original tonality as intended by headphone manufacturers. But a handful of low impedance multi-BA and hybrid IEMs will be affected to the point where the bass gets attenuated and the treble is a little boosted. The degree of this effect will vary, and I have examples in pair up section of this review. You can't ignore it, but it's also not the end of the world since you can use iEMatch (
http://amzn.to/2tVhc1W) from iFi (either 3.5mm or 2.5mm version) to "restore" the sound.
Comparison.
In this comparison I used a few different IEMs, all volume matched, to compare how R6 stacks up against some other DAPs.
R6 vs FiiO X5iii - R6 has a more neutral revealing sound while in comparison X5iii is smoother, warmer and less resolving. With R6, bass is more articulate and better controlled, and there is more sparkle in treble. Two things that stand out for me, R6 has a blacker background (very noticeable) and a wider soundstage. X5iii has quite a noticeable hissing. Also, from a technical performance, R6 sound has more layering, better separation, better dynamic expansion. R6 sound is just cleaner and more detailed. And the same with Android performance, R6 is faster, more responsive, and more capable as a standalone Android device. X5ii does have dual uSD, more storage, and it has low OI, but in terms of sound quality and Android performance, there is a big gap between these two.
R6 vs Cayin N5ii - There are a lot of similarities in sound when comparing these two. Both have a similar soundstage expansion, though I noticed with some IEMs R6 sounds a little wider, not sure if OI and/or using iEMatch has anything to do with it. For example, I noticed this difference with U18t, while with IE800s connected directly - it was nearly identical in both soundstage and tonality. So, lots of similarities in terms of being neutral and with a more revealing tonality, though in some cases where I had to use iEMatch, the bass was a little more neutral and treble had a touch more sparkle. Both have a nice dynamic expansion of the sound and a black background. In terms of a technical performance, R6 has a little edge in layering, separation, and transparency of the sound. Besides output impedance, the biggest difference here is Android interface where R6 feels like a smartphone with a higher quality display and a very snappy Android performance. In contrast, N5ii presents itself as DAP first and Android device with Google Play and streaming capability second, like an add-on. Also, N5ii has an advantage of a dual uSD versus a single card in R6.
R6 vs FiiO X7ii - Similar soundstage expansion, though R6 is just a little wider. Also, R6 has a blacker background. Both have a very similar neutral revealing tonality with excellent retrieval of details, punchy extended bass, layered detailed mids, and well defined airy treble, though in some pairs up with R6, I hear treble being more extended. Besides the sound, there are also many feature similarities with both being a full Android DAP. But while they both support Bluetooth and wifi, and have open Android OS with pre-installed Google Play Store, the actual navigation and Android OS experience is on a much higher level with R6, while X7ii is slower and not as responsive as R6. Both have the same internal and external storage, but X7ii also has an advantage of replaceable amp modules.
R6 vs theBit Opus#3 - While I hear R6 soundstage to be a little wider, in terms of the sound signature these two are very close with a brighter revealing neutral tonality where in a blind test it's hard to even tell them apart. Even their technical performance, in terms of layering and separation of the sounds is very similar. They both have a more neutral, yet rather articulate and punchy bass, and a little brighter upper mids and crisp airy lower treble. Both have a similar black background. What sets them apart are the physical features. While #3 has 64GB of internal memory vs 32GB of R6, they both have one uSD. Also, both support Bluetooth and Wifi, but #3 has Android running in the background and it's closed, to the point where you have to side-load apps. R6 has a full open Android support with access to Google Play where you can easily install any app. So, while tonality and overall sound performance might be similar, if you want a true powerful android DAP, R6 is the way to go. Plus, 8-Ball sound shaping effects of R6 are a huge plus.
R6 vs Cowon Plenue R - Both have a very similar soundstage expansion, in width and depth. The difference here in R6 being more revealing and a little brighter while PR sound is smoother and a touch warmer in comparison. Both have a similar bass emphasis, though the tonality of PR gives it a little deeper perception. I'm also hearing R6 mids to be more layered with a little better separation of sounds. Both have a nice extended airy treble. While R6 has its MageSound 8-ball, Plenue has its advanced JetEffect. Both have Bluetooth to pair up with wireless headphones or speakers. That’s about it for PR, while R6 is a full android dap with Google Play store support to load any app, including streaming ones. In terms of storage, PR 128GB of internal storage and uSD card are superior to 32GB of R6 w/uSD. Also, PR has better battery life.
Pair up.
This is probably the most important section of my review because it covers how R6 pairs up with different full-size headphones and IEMs. There was no need to even consider iEMatch until I switched to IEMs.
Audio-Technica ATH-R70x (open back, full size dynamic) - wide airy soundstage expansion, a very balanced sound signature with more emphasis on mids, not necessary being mid-forward but just making them standout with a more natural tonality and effortless retrieval of details. Bass is very neutral, extends deep with a nice rumble, but a very neutral quantity, and the same with mid-bass, with an overall bass being articulate and layered. Treble has a nice neutral sparkle as well, not too harsh or rolled off, just a perfect amount for a natural definition of the sound.
Oppo PM3 (planar magnetic) - above average soundstage width with more depth. The sound is brighter in tonality in comparison to other pair ups, PM3 sound can get easily congested with some DAPs, here the sound was closer to neutral with a more revealing tonality, still smooth and a little laid back, not very layered or with improved separation. Warm sub-bass extension with a slightly elevated mid-bass - bass is typical of PM3, being slower, not as articulate, but it has a better control in comparison to pair ups with other DAPs where bass usually spills into lower mids. Here, lower mids do have full body, but they are not muddy or congested. Upper mids are smooth and detailed, while treble has a nice well-defined sparkle.
Audeze EL8C (planar magnetic) - wide/deep soundstage and a very fast sound, typical of planar magnetic driver performance. Bass is very neutral, being all about quality rather than quantity when it comes to sub-bass extension and mid-bass punch. Lower mids are lean, and the big emphasis here is on upper mids and treble. Mids are detailed, actually down to micro-detailed level, but they are also cold and more analytical. And the treble is a little too piercing, making the sound too revealing and less natural. It wasn't my cup of tea, but I'm glad to report there wasn't metallic sheen in the sound, like I find in some other pair ups.
Beyerdynamic T5p 2nd (Tesla, full size dynamic) - wide/deep soundstage, almost on a holographic level, and the overall sound is very balanced, with a natural neutral-revealing tonality. Sub-bass has a nice deep extension, but the quantity of the rumble is a little north of neutral. Mid-bass has a nice fast punch, with an overall bass being very articulate, layered and well controlled. This leads to a more neutral lower mids and micro-detailed upper mids, but with a more natural detailed tonality. Treble is crisp and airy, gives a very good definition to a sound.
VE ZEN (320 ohms earbuds) - above average soundstage width with more depth. The overall tonality is a little brighter and more revealing in comparison to how Zen pairs up with some other DAPs where it usually sounds a little smoother and more organic. The sound is actually faster and a little leaner. Bass goes down to a deep sub-bass extension with a very nice rumble. Mids bass has a fast punch, this is probably the "fastest" I heard Zen bass, being very articulate and well controlled. Lower mids are a little leaner, and upper mids are natural, transparent, with an improved retrieval of details. Treble has a nice sparkle, not too bright or too crisp, with a good extension.
Next, I tested a lot of IEMs where I made a note about pair up with and without iEMatch.
Sennheiser IE800S (DD) - the sound is balanced with a nice deep sub-bass extension, great mid-bass impact, very natural detailed mids, and a nice crisp airy treble. iEMatch reduces some of the treble definition, taking away a bit of sparkle and airiness. Wide soundstage. I prefer a direct pair up here.
Beyerdynamic Xelento (tesla DD) - very expanded soundstage, tastefully done v-shaped sound with upper mids pushing just a little bit back. Bass goes deep with a healthy sub-bass rumble and fast punchy mid-bass, lower mids are neutral while upper mids are natural and detailed, nice organic tonality, and treble has a nice controlled sparkle. With iEMatch mids are pushed more back. Direct pair up is preferred.
Campfire Audio Vega (DD) - nice soundstage expansion, a typical expected L-shaped sound sig, perhaps more like a reversed J-shaped since I can also hear a nice treble sparkle. Bass goes deep with lots of sub-bass and slower mid-bass, overpowering mids which are smooth and warm, and pushed back in their presentation, and a nice crisp treble. With and without iEMatch the sound is the same.
Campfire Audio Andromeda (5BA) - here, iEMatch is definitely a must-have because without it the sound has a very neutral bass with a rather forward upper mids and splashy treble and a very noticeable sibilance, which you usually don't hear from Andro. Once iEMatch added, it transforms into the sound I'm used to while listening with other sources - you get a fast mid-bass and a nice sub-bass extension which shines more with quality rather than quantity, neutral mids, detailed upper mids with a little brighter and more revealing tonality and crisp airy treble. iEMatch definitely brings Andro back to its fun signature.
iBasso IT01 (DD) - another example where iEMatch is not necessary, and it actually reduces the quality of the sound. Here with a direct connection you get a fun v-shaped signature with a deep and powerful sub-bass rumble and elevated mid-bass punch, neutral clear lower mids and revealing brighter upper mids, and crisp airy treble with a nice extension. iEMatch reduces the sparkle of the treble, turning v-shaped fun into a more L-shaped sound. I definitely prefer a direct pair up here.
iBasso IT03 (DD/2BA hybrid) - here, using iEMatch is actually a big plus. Directly connected, sub-bass and mid-bass becomes very neutral with upper mids and treble pushed more forward, and even some emphasis on sibilance. Once you connect iEMatch the sound change is back to expected tonality with a nice sub-bass rumble, faster mids-bass punch, a little pushed back but still detailed and brighter mids, and well-defined and controlled crisp treble.
Westone W80 (8BA) - low impedance multi-BA, you can safely guess iEMatch will be a welcome addition here. Direct connection gives you a slightly mid-forward signature since bass is more neutral and upper mids/treble are elevated. With iEMatch, the sound is balanced with a nice sub-bass rumble and punchy well controlled mid-bass, not too fast or too slow, neutral lower mids, natural detailed upper mids, and a crisp and well controlled treble. Very enjoyable pair-up, as long as you keep iEMatch handy.
Ultimate Ears UERR (3BA) - didn't expect this one, but with or without iEMatch the sound is nearly identical. I hear a very neutral natural tonality with a decent sub-bass rumble, polite mid-bass much, neutral lower mids and natural detailed upper mids, and well-defined treble with a controlled sparkle. Actually, a very good pair up.
Noble K10UA (10BA) - another surprise where the sound is the same with and without iEMatch. You get a very well-balanced sound signature with a good sub-bass rumble, elevated fast mid-bass punch, neutral lower mids, revealing brighter upper mids, and crisp airy treble. Plug these in directly and you are good to go.
HiFiMAN RE2000 (DD) - with a single dynamic driver I was expecting that iEMatch is not necessary, and found it connected directly to sound nearly the same as other sources, but adding iEMatch actually took down a layer of brightness from the upper mids and lower treble, making the sound more pleasant and less harsh. You still get a great dynamic driver quality sub-bass extension and surprisingly articulate overall bass performance, mids are more analytical and on a brighter side, while treble is crisp and airy, but upper frequencies are smoother in comparison to direct connection. This is just a matter of personal preference.
64 Audio U12 (12BA) - this is how the original U12 was intended to sound! It's not a secret that this IEM was tuned using higher OI source for performing stage musicians who use higher impedance wireless packs. The difference between R6 and any other DAP is around bass where with R6 bass is no longer bloated and overwhelming, you get a textured sub-bass rumble with a punchy mid-bass; with bass being well controlled without spilling into lower mids, and lower mids being north of neutral with a nice body but not muddy or congested, while upper mids are smooth and natural and still detailed, treble is well defined but not as crisp or airy. Adding iEMatch makes sound a little congested around lower mids, so direct connection is desired here.
64 Audio U12t (12BA) - learning a lesson from the original U12, U12t now features LID tech where the sound should be identical from any OI source. And indeed, when compared between R6 and other low OI daps - the signature is the same with a balanced sound sig where you have a nice bass impact, not too overwhelming and well controlled, neutral lower mids with a more natural-revealing tonality of upper mids, and crisp airy treble thanks to TIA driver. Adding iEMatch in series doesn't affect much the bass or the lower mids, but it does make upper mids and lower treble a shade smoother if you want to tone down the TIA sparkle.
64 Audio Fourte (DD/3BA hybrid) - this is the one pair up so far where the synergy between a dap and iem wasn't there, regardless of iEMatch or not. Adding this adapter does takes an edge off the upper mids/treble which could be a little too vivid for some, and regardless of the adapter the bass was still very accurate and with a nice sub-bass rumble and mid-bass punch, though both rather polite in quantity. But the main problem here were the mids which sounded a bit muffled to my ears, not the same as other DAPs. For me personally, this is not a good pair up.
64 Audio U18t (18BA) - talking about night'n'day difference, that's how I can describe the sound of these iems with and without iEMatch. Without, you have a very mid-forward bright signature with a neutral flat bass. Once iEMatch added in series, U18t transforms with a deep textured sub-bass rumble and fast mid-bass punch with a slightly boosted quantity, neutral lower mids, natural micro-detailed upper mids, and crisp airy extended treble. This is not even a question, if you want to use U/A18t with R6, iEMatch is a necessity.
Empire Ears Legend X (2DD/5BA hybrid) - the clever crossover design of this hybrid reassures there is no need to worry about iEMatch because with or without it the sound is the same. You get a powerful L-shaped signature with a deep impactful sub-bass rumble and elevated mid-bass slam, with bass being well controlled despite being a force of nature that you feel in your chest. Mids are very natural and detailed, not really pushed back, but being more in a background due to elevated bass, and the same with a treble which is well defined and with a polite crisp and airiness. This is a basshead audiophile iem and it hits hard with a bass. Actually, even harder in comparison to other dap pair ups.
Conclusion.
When you are entering a competitive market of today's mid-fi DAPs, you need to be able to stand out from the crowd. Many manufacturers respond to this challenge by offering unique looking designs or adding extra features or cutting corners to lower the price. Unless you have budget and resources of Sony or A&K proportions, smaller manufacturers focus on finalizing the hardware before the release, and then hoping to catch up with fw updates to fix remaining issues. Hiby is in a unique position where they are the one who help others to "fix" their fw issues, and as a result they are one step ahead of competition when it comes to fw/sw. And with that power, they're also in a position to cherry pick their own hw because they know how to optimize its performance.
That's exactly what happened in the debut release of Hiby R6 DAP. They picked a higher end SoC processor, the most RAM in comparison to other Android DAPs, top quality display, two premium ESS DACs, and also premium LPF and headphone amplifier opamp components. We are not just talking about another Android DAP release, but Android 6.0 with DTA (direct transport audio) architecture to ensure bit-perfect output (bypassing Android SRC). And this is not another ES9018 dual dac release, but they actually used higher end 9028 dac. And not a gimmicky balanced output, but actually BAL output with more than double the power of SE. And not just usb-c port because it's a new popular standard, but actually with a support of QC3.0.
It would have been nearly perfect, except for high output impedance which could be an issue with some IEMs. I intentionally put extra effort in pair up testing with many different IEMs/headphones to describe the effect of OI. And as you can see, it's not really the end of the world, and could be resolved with iEMatch. I'm not making excuses for Hiby, they learned their lesson and the upcoming R3 release already has lower output impedance. Also, I don't want people to get an impression that R6 is only about fast Android performance. It also has a very impressive sound performance, along with a collection of MageSound 8-Ball effects to further fine tune the sound to perfection. Yes, you might have to invest into iEMatch, but it's a small price to pay when you are looking for a top Android performance high-res DAP.