Alright so K11 R2R mini review, comparing directly to my Topping MX3S as to me this is a personal benchmark for sound dynamics, not necessarily power, as it's only 700mW x2 from the single ended vs the 1300mW from the balanced output on the R2R (the volume at 40% on the R2R is similar loudness as the MX3S at 60% with both on high gain).
I've always said the MX3S to me has the "NAD Sound", an almost analogue sound signature (just without the background hiss of analogue amps) that I've been a huge fan of since I had the NAD C3xx Bee amps back in the 90s and early 2000s, a sound that the later solid state NADs also embodied, and now Topping do too at a fraction of the cost of a modern NAD and don't fail just outside of warranty like my last 3 NADs did
For ref:
- Headphones: Arya Stealth with Voarmaks memory foam velour pads that remove the harsh brightness peak that HiFiMAN are renowned for. No impact on any other part of the sound.
- The R2R is set to high gain, volume 40%, non-oversampling mode, 4.4mm balanced output. Windows defaults to 32-bit, 48KHz.
- The MX3S is at high gain,volume 60%, treble set to +3, bass to +2, 3.5mm single ended output. Windows defaults to 24-bit 48KHz.
- Both connected to the PC via USB in the dedicated USB2 ports on my mobo.
The songs I've been repeating between the two, and why I chose these tracks from my
custom playlist of "headphone" tracks:
- Nick Cave & The Bad Seeds - Bright Horses // Has a constant mellow vocal score with really awesome texture in the main singers voices
- Neil Young - Heart of Gold (2009 remaster) // Awesome stereo imaging with instrument placement that impacts perfectly in their placement in each ear
- Sara K - All Your Love (Turned To Passion) // Constant guitar strings in and out along with a nice low bassline, Sara's voice is beautifully textured here with great timbre
- Club For Five - Brothers in Arms // Primary male vocal with female/males mixed vocals in the background
- 8D Tunes - I Kissed A Girl // This is one of those remixes in 8D audio, the panning holophonic presentation of this track is excellent on planars
- 8D Tunes - Beggin // Same as above
- The Cat Empire - Hello // A very busy song and will show up any muddying by amps/headphones that can't keep up with its energy
- Hazel English - California Dreamin' // A really tight and an energetic kick drum that covers the whole song with once again amazing timbre vocals
- Simi ft Asa - Messiah // A nice and spatial track that also has a mid/low bassline the chorus sections
- Madonna - Lucky Star // Quite a bright song by nature, I found this song to produce sibilance on certain amps and/or headphones.
- Queen Omega - No Love Dubplate // If you haven't heard this one then you can truly appreciate her voice even on youtube!
Other headphone amps I am referencing against since I've had those recently too: Topping DX3 Pro+, Onix Alpha XL1, Questyle M15i, Fiio K7.
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Volume pot/dial: K11 R2R has a nice quality volume dial/pot. The Fiio K7's dial and pot were both quite terrible by comparison as it felt cheap and the volume increments in sound were stepped instead of being smooth. The DX3 Pro+ has a bugged volume pot, each increment has a nice tactile and audible click, but quickly going up or down several % will see the digital volume miss increments. By comparison, the MX3S and the K11 R2R have near identical volume pot/dial feel and performance. They are notched internally like a mouse wheel and no increment values are missed however fast I turn the dials. The Topping volume dial itself is physically longer than the K11 R2R dial, though the R2R's dial is knurled so has added grip under the fingers whereas Topping dials are smooth which meant I had to DIY a black custom rubber band around it to add single finger grip to use the dial without the remote.
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Display: The MX3S, DX3 Pro+, XL1 and R2R have excellent displays with plenty of info and options. R2R has no remote though, so the user interface is just via that dial, seems very well refined compared to the janky dial of the K7.
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Anti-slip feet: It's kinda weird that none of these amps come with rubber feet that are of any use, all of them still cause the units to move forward on the desk if you are plugging in a headphone cable or pressing in the volume dial button. I ended up fitting thicker stickier rubber feet off Amazon which is much better.
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Heat: R2R does not get warm, only slightly warm just above room temp. By comparison both toppings get noticeably warm to the touch, K7 also got warmer, Both the Questyle M15i and Onix Alpha 1 got hotter still to the touch, though to be expected given they are compact devices with a lot of power being output.
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Sound: Between Topping MX3S, DX3 Pro+, Questyle M15i, Onix XL1, the R2R seems to offer refinement in treble control and vocals especially. Brightly mastered songs like Madonna's Lucky Star are more tolerable even at high volume. This song is a benchmark on how well behaved headphones/amps are playing it at high volume which would otherwise lead to fatigue.
Note: When changing the gain setting, if you have had the volume at high levels on low gain then setting to medium or high gain will be excessively loud if audio is playing so make sure to lower the volume before changing to a higher gain first, the loudness curve is quite considerable between all 3 gain modes:
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Soundstage & imaging: Whilst the Topping MX3S and DX3 Pro+ are about the same, the DX3 has no tone controls so isn't as fine-tune friendly but does sound almost perfect out of the box, or did for the week is was alive when I had it. Stereo imaging of the R2R seems to be the most organic thanks to the vocals and instrument separation, not huge differences but enough to appreciate them, especially the timbre of voices. The Fiio K7 did not sound anywhere close to this, it was too bright sounding and not well suited to planar headphones. You'd need to use Peace/APO to EQ out that brightness as a result for those dead set on the K7...
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Noise floor: Zero audible noise at any volume in any gain setting even though some reviewers said they heard some background noise on other headphones/IEMs.
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Features: R2R's NOS vs OS modes were only subtle differences but it did depend on the song being played. I think to my ears NOS mode sounds slightly better, both sound excellent though. 3 modes of gain on R2R, the others only have 2 gain levels. Both RGB logo on the top and display can be customised, the UX is intuitive and easy to use.
Both the XL1 and M15i are excellent dongle DACs, the XL1 especially given it costs £87 and sounds nearly the same as the M15i, but the Topping MX3S is still more refined in subtle ways thanks to having tone controls, slightly wider soundstage than the dongles but the M15i had the better resolution of the three, more articulate in the highs but that's down to having onboard tone controls which none of the other amps have. The R2R seems ncely balanced and natural out of the box with no need to tone control or software EQ anything at all. Everything has an analogue/organic feel to it and that's likely down to the R2R architecture. I can only imagine what the 4 figure R2R DACs sound like if this is what a £154 one is capable of.
R2R has enough features and sound quality whilst retaining that "NAD sound" that I like, just like the the MX3S but with refined sound overall, so both will be my desktop setup, MX for the speakers, R2R for headphones. It produces more ear-pleasing sound than the annoyingly bright Fiio K7 (one of the reasons I returned it) and doesn't have the quirks I hated about the DX3 Pro+ (which also died a week into ownership).
I also read/watched all of the R2R reviews since it launched and a handful stated that planars are still bright with the R2R. one guy had some older HiFiMANs and said it was too sibilant via the R2R whilst also not being very good at resolution. This is directly the opposite of what I am hearing with the Arya Stealth. The same reviewer even stated the R2R has 5 USB filter modes, it does not. I think some reviewers just don't pay too much attention lol.
TL;DR version: K11 R2R combines everything I liked about all of the headphone amps mentioned here into a simple easy to use device. The only fault I can mention really is the menu driven gain control and no quick return to the home screen if you accidentally change to a high gain and get deafened by extremely loud music as you need to long press the dial to return home or cycle the menu to the return option.
If anyone else is still waiting for UK stock, then you may as well order off Ali Express unless you must have UK warranty, same price basically and no customs charges. UK stock is supposedly end of Sept but that's not set in stone iirc.