Review: HiBy R6 Pro II

Select pairings

HiBy Zeta ($1,299). HiBy’s flagship tribrid IEM, Zeta has been one of the audio highlights of the year for me. It has a punchy, warm-bassy, but also very clear and relaxed tonality that makes for easy listening with my entire library, and adds clean weight to my favourite bass tracks for good measure. 

Of the three drivers I tested with R6 Pro II for this review, Zeta is by far the easiest to drive, and gets really loud at 35/100 in low gain. R6 Pro II gives me all the bass slam and control I’m expecting with Zeta, but also adds some clarity to the lower regions. With a slightly forward upper midrange, Zeta can sound a hair too hot on some tracks, but on the whole it sounds clear and very detailed with the new Pro, and a touch of MSEB takes care of any upper midrange nasties. Treble has that gently Zeta nature to it, but is also a touch drier than I’ve heard with Zeta on other DAPs. 

Overall I feel this pairing is one of those that’s made for each other. R6 Pro II makes the most of Zeta’s technical performance. No doubt HiBy took Zeta into account when tuning R6 Pro II, and it shows. At almost twice the price of the DAP, Zeta is not a cheap purchase, but the combination of the two for ~$2,000 makes for an outstanding, high-end audio experience for those that gel with Zeta’s sound profile.   

Sony IER-Z1R ($1,799). My IEM of choice and consummate all-rounder, the Z1R/R6 Pro II pairing is surprisingly not the best I’ve heard the Sony perform. Z1R is all about liquid sub-bass, clarity and stage, and I feel R6 Pro II, while maintaining those qualities, also adds a touch too much clarity, resulting in a slightly drier sound than I’m used to. 

That’s not to say I don’t enjoy it the combo, I just enjoy it less compared to hearing Z1R off DAPs like WM1Z, RS8 or DX300 MAX. R6 Pro II has plenty of gusto and drives it just fine, with Z1R getting as loud as I need it by the halfway volume mark on middle gain. 

Objectively speaking, those that crave detail, clarity, speed, and an ink-black background will find plenty to like here. You’re not going to get oodles of warmth, but rather a clean, balanced tonality, with excellent imaging, layering, separation and staging. While female vocals might be on the drier side here, male vocals are well represented, and don’t sound as recessed as Z1R sometimes tends to render them. 

Overall I’d give the pairing a solid 8 out of 10, but knowing that Z1R is usually in the upper 9’s for me makes me less enthusiastic about it with the new Pro.   

TGXEAR Serratus ($200). This one was more a litmus test for the driveability of the R6 Pro II’s seemingly modest power output. TGXEAR’s Serratus is easily the best sounding earbud I’ve had the pleasure of hearing. It’s also very hard to drive properly with its high (300-ohm) impedance and low sensitivity. 

I’m glad to say I have no issue using Serratus with the new Pro. I can get it up to a moderately loud volume at 60/100 in high gain, and it sounds sublime. Everything from stage structure to sub-bass extension, midrange purity and treble quality is intact, and I don’t feel like I’m losing anything by way of sound quality, headroom or driver control with this pairing. Also, since I listen fairly loud anyway, it’s unlikely most people will even need this level of output. 

With Serratus and R6 Pro II, you’re getting a matchup that delivers high-end performance, especially for lovers of classical and jazz music, for less than $1,000. Sure, you’re making other compromises with earbuds, but in terms of pure sound quality, I’m not sure I’ve seen this degree of competency at this price point before. 

Select comparisons

HiBy R6 III ($499). You could say the recently-released R6 III (reviewed here) is R6 Pro II’s distant cousin. After all, the original R6 Pro was derived from the original R6. That’s where the similarities end, however. R6 III is rooted in the past, with now-ageing ESS 9028QM DACs and the same angular design motif of the R8/R6 2020/RS6, whereas R6 Pro II is very much looking forward, with the latest AKM flagship DACs and an all-new styling that may or may not be carried forward into future DAPs. 

It’s not all plusses for R6 Pro II however. Weight is similar, but R6 III looks diminutive side-by-side with the new Pro – which possibly makes it a better option for those wanting the smallest, lightest and most portable DAP without compromising modern features and performance. R6 III also has more stamina, which makes it better suited for full-day use, and some will prefer the volume dial and angled buttons. 

Sonically, it’s a one-sided affair in favour of the new Pro. Whereas R6 III is perfectly acceptable, even very good, at the sub-$500 level, it’s not really a standout from its competitors, whereas R6 Pro II occupies the very highest rung at its price point, in my opinion. R6 III’s sound is clean and clear, with an excellent ESS implementation that mostly overcomes the ‘Sabre glare’, but R6 II Pro is bigger, bolder, with a darker background and significantly more resolution across the FR. 

To my mind, R6 Pro II makes R6 III redundant, at least in terms of audio performance, unless you have a thing for ESS DACs and their distinctive sound. That the two are priced $250 apart means the R6 III would only really be attractive to those wanting a much smaller footprint and longer battery life, or don’t gel with R6 Pro II’s styling.

HiBy RS8 ($3,299). At the other end of the scale, HiBy’s current flagship (reviewed here) is the epitome of advanced refinement, with a gorgeously organic, authentic analogue voicing from its R2R internals. While some might hear R6 Pro II as matching or even edging out RS8 in raw technical performance, that comes at a cost of last-mile polish, control and effortlessness, which is ultimately what you’re paying the big bucks for. 

Feature-wise R6 Pro II and RS8 are fairly similar. Same Android platform, same SoC. RS8 has more memory (6GB RAM vs 4GB), more internal storage (256GB vs 64GB), and a battery that seems to last forever. Battery life alone is a first-round knockout in favour of RS8, so if that’s a priority, and you have the budget, the choice is easy. 

HiBy has done a very good job tuning the dual Delta Sigma DACs on the R6 Pro II, so it doesn’t sound too ‘digital’, and at the same time, they’ve tuned RS8 with less warmth and wetness that’s typical of many R2R DACs, giving it enough technical muscle to please more demanding audiophiles. Still, the chasm between the two is vast, and I can see someone owning both as a complementary pair: R6 Pro II as a more portable, on-the-go option, and RS8 a refined, muscular and musical home companion. 

Continue to closing thoughts…



Picture of Guy Lerner

Guy Lerner

An avid photographer and writer 'in real life', Guy's passion for music and technology created the perfect storm for his love of portable audio. When he's not playing with the latest and greatest head-fi gear, he prefers to spend time away from the hobby with his two (almost) grown kids and wife in the breathtaking city of Cape Town, and traveling around his native South Africa.


2 Responses

  1. Fabulous review! With so much detail and thought.

    Any view on how these compare to the shanling m6 ultra? And would pairing the R6P2 with an amp like the Topping NX7, be able to drive full sized headphones like say Sennheiser HD650s?

    1. Thank you. I have not used the Shanling so can’t say, but yes, connecting the R6 Pro II via line-out to an external amp will easily power full-size headphones.

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