The R6 implements two ESS Saber ES9028Q2M Pro chips, one per channel. It’s a nice upgrade over the very popular 9018xxx, and one that has proven to be more balanced in the various implementations I’ve tested; lacking the glare associated with Saber’s previous generation chip. However, though the R6’s dual ES9028 setup may sound similar to the much pricier iBasso DX200, it should be noted that iBasso are using the Pro variant, as does the Fiio X7 MKII (but only one).
The Pro was designed for desktop solutions, with a considerably higher power draw and extended features. In an optimal implementation, both can provide similar dynamic range and SNR (and both are excellent), and both chips boast wide file support outlined in further detail on Hiby’s website here.
It goes without saying that this is easily among the best solutions available at present, and despite using the portable Q2M variant, Hiby’s implementation is clean and resolving. And like the other 9028 sources I’ve tested, the R6 lacks any middle-treble glare while upholding a high-level of detail retrieval and resolution. Moreover, it retains its technicalities despite lying on the musical side in signature.
The R6 implements the 2x OPA1612 and 2x TPA1602A opamps, one per channel. It delivers a very potent 300mW RMS through its balanced output and a still very respectable 120mW RMS through its standard output, both into a 32ohm load. Its TRS output is roughly on par with Fiio’s AM3A, and though it does lack the ability to swap in a more powerful module, its balanced output is 50% more powerful than Fiio’s standard implementation.
In use, the R6 has no issue driving IEMs and portable headphones to potential; it even does a fine job powering larger headphones like the HD6XX though they do miss some control when compared to more powerful solutions. Still, Volume is no issue and noise is practically imperceptible, even when listening through the ridiculously sensitive Campfire Jupiter. I did notice some interference when WiFi was active but it’s not hugely obtrusive, similar to the original Fiio X7. Still, it may bother sensitive IEM users who use a lot of music streaming services.
This brings us to the main caveat of the Hiby R6, its output impedance. For those unaware, you can read nwavguy’s excellent write-up here, which details all the specifics. The main takeaway is the 1/8th rule which states that the player’s output impedance should be under an eighth of the attached earphone/headphone to avoid dampening issues and signature alteration. At 10 ohms, the R6 can and does have a significant effect on a lot of IEMs, the vast majority of which lie well below 80ohms in impedance. However, single driver earphones are mostly exempt from this rule as most have a flat impedance response.
As a result, I found the R6 to perform best with single dynamic driver in-ears such as the Beyerdynamic Xelento and Sennheiser ie800S, in addition to cheaper offerings such as the TFZ King Pro. Its output impedance had minimal, if any effect on their signature and all were rewarded with a spacious, dynamic and well-controlled sound. The R6’s enhanced sub-bass and slight darkness isn’t always the best pair to the generally warmer tuning of these earphones, but it’s still a nicely transparent source aided by impressive resolution.
All of the following comments will be using my Custom Art Fibae 2 which also features a flat impedance response. This enables its signature to remain the same between sources of differing output impedance, allowing the individual characteristics of the source itself to shine through. As always, testing will be conducted through an inline switcher and by ear, with all sources mentioned in this review volume matched using an SPL meter.
At first, I didn’t find myself captivated by the Hiby R6. This was mainly because my earphone of choice was of a low-impedance, multi-driver design. However, beyond that, the R6 also wasn’t what I was expecting from a Saber 9028 device; it simply seemed to lack some vibrancy and clarity when coming from the Fiio X7 II and the iBasso DX200.
However, further critical listening revealed that the R6 is a very resolving source. And though it is definitely more on the musical side of the spectrum, the R6 remains transparent enough to permit wide synergy (when disregarding its OI), the hallmark of a proficient source. To further clarify, the R6 delivers a full sound with a slightly darker high-end. Its sound is very well controlled and extension is up there with the best, delivering both high-resolution and a large soundstage. The R6 is also a little more aggressive in its detail presentation, granting a richly textured sound. Please take into account that, as this is a source device, these are small deviations from neutral that can’t be likened to those between headphones and earphones.
The R6 diverges from the analytical sound expected from Saber sources, delivering a robust low-end with a focus on depth and impact. This stems from well-extended and slightly elevated sub-bass that heightens slam, a good match for balanced armature in-ears. In addition, as mid-bass is fairly neutral, the R6’s low-end still sounds nicely transparent and its tone remains neutral; thereby avoiding muddiness and bloat. This style of tuning also grants the R6 a natural bass note size that contributes to its well-separated presentation despite deeper emphasis.
The R6 also excels through its tightness and control, producing defined and focused notes. Though decay is a touch longer than more analytical sources, the R6 is impressively dynamic, exceeding most similarly priced DAPs. This is imbued through a combination of its aforementioned enhanced impact, in addition to great separation on account of the Hiby’s excellent mid-bass control and clean presentation. It isn’t a reference source in the same sense as the iBasso DX200, but it’s only a little more sculpted than sources like the Fiio X7 II, which bodes well for the versatility of its synergy.
The R6 has a slightly darker midrange with a more laid-back vocal reconstruction. This character can be primarily attributed to two factors; a bolstered lower-midrange that creates a full-bodied presentation, and a slightly attenuated upper-midrange that creates smoother, cleaner vocals. By contrast, the R6’s centre midrange remains fairly neutral in quantity if not very slightly elevated, thereby maintaining pleasing vocal presence. Its slight upper-midrange dip can make female vocals and instruments such as strings sound a little distant though, it isn’t sculpted to the extent of thickness or congestion.
As a result, the R6 doesn’t excel with clarity, but it also never sounds veiled due to its higher resolution combined with great space and separation. This also grants the R6 with nice background detail retrieval, so it’s one of the more resolving sources I’ve heard around this price despite not being especially bright or analytical in any way. This style of tuning works in conjunction with a slight lower-treble lift that serves to increase articulation, helping to prevent overshadowing of upper-midrange elements. The product is a source that excels with timbre, sounding very smooth and natural but not explicitly warm. And though the R6 doesn’t bring fine details to the fore like some others, its sound is clean, nuanced and doesn’t grate on the ear over time.
The R6’s high-end is well coordinated with its midrange, maintaining a slightly more laid-back presentation prioritising cleanliness over clarity. That said, lower-treble has slight emphasis imbuing energy and articulation into its high-end. And, in addition to being slightly more aggressive in its treble attack, the R6 also retrieves a great amount of detail. Its emphasis is also gradual enough to maintain realistic instrument timbre; guitar strums sound crisp yet richly bodied and strings are delivered with accurate texture. Treble gently falls off above, before extending linearly into the highest registers.
This dip into the middle-treble results in a more laid-back presentation, especially with regards to strings. However, it also grants the R6 with a dark background that strongly contributes to its overall sense of cleanliness. Still, the R6 has audibly muted sparkle and shimmer which may not please lovers of Japanese or Korean music. That said, the R6’s excellent extension contributes to its high resolution, and the Hiby is ultimately a very composed and well organise DAP; excelling with all levels of mastering quality through a combination of excellent detailing, resolution and control.
The R6 has a spacious stage with especially impressive width. It’s clearly more open and layered than the Fiio X7 II but lacks a little depth compared to the pricier iBasso DX200 w/AMP5. This can partly be attributed to its laid-back high-end that emphasizes its sense of space, though its fullness also provides density to its layers. As such, I find the R6 to provide very convincing imaging; its natural body and expansive stage dimensions working in unison to provide coherence while maintaining separation. Separation, in particular, is quite standout as the R6 has zero glare and well-considered tone throughout. Combined with its cleanliness, every frequency range remains well-delineated and defined.
The balanced output has two and a half times the output power of the regular TRS output but drops runtimes from 12hrs down to 7hrs. It’s using the same amp chips as the regular output so don’t expect huge changes apart from a slight increase in volume. I used an SPL meter to ensure both outputs were as similar in volume as possible when ABing, and subjectively hear some differences between the two. Through balanced, I experienced a slightly deeper bass response with greater impact. It also has a different soundstage presentation that sounds larger, most notably with regards to width in addition to increased separation. That said, I don’t feel that its presence hasn’t compromised the quality of the regular TRS output.
Although the R6 is undoubtedly a very nice sounding DAP within its tier, its output impedance does create inconsistency between earphones. As the effects can vary on a case by case basis, I’ll provide comments on the Hiby’s output impedance using a variety of driver types and impedances. Comments will be relative to the Fiio X7 MKII (OI <1.2ohms) with which I am most familiar.
Beyerdynamic Xelento (16ohm, dynamic): The Xelento is a resolving low-impedance dynamic driver earphone. It has excellent synergy with the R6, benefitting from strong dynamics and a spacious, separated stage. Actually sounds a little more balanced due to improved control, especially with regards to bass. More transparent midrange.
TFZ King Pro (55ohm, dynamic): Not overly affected, slightly darker and fuller in line with impressions through the Fibae 2. Nice synergy, a little more bass depth, clear mids, a little more natural. High-end is very detailed, nice shimmer and extension. Spacious stage.
Noble Audio Katana (~20ohms, 9-driver BA): Potentially terrible pairing given the Katana’s driver count. However, its slightly higher impedance lends it well towards the Hiby as does its brighter signature (subjectively). Bass lacks a touch of extension but the R6’s sub-bass lift well compensates. Upper-mids become notably more laid-back as do highs. Still plenty of crispness, even sounds a bit cleaner due to smoother middle-treble. Similar resolution and larger stage dimensions.
64Audio U6 (22ohm, 6-driver BA): I experienced similar signature changes to the Katana; noticeable, but not destructive. Most notable was the R6’s more laid-back female vocals, slightly more aggressive lower-treble and cleaner background. Resolution remained high as did bass control. I did miss a little air and clarity up top, but the R6 sounded appreciably more spacious due to its more laid-back presentation and equally strong extension.
Hyla CE-5 (8.9ohm, 4-driver hybrid): The Hyla is very source sensitive, providing a worst case scenario. Immediately skewed signature, considerably darker and more veiled. Bass is dominant and bloated, lacking control. Mids are smooth but more recessed and highs sound very muted and distant. Notable drop in volume. The CE-5 was unlistenable from the Hiby.
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