The highs seem like there may be a spike or peak somewhere in the upper mids or treble, but not in a painful way. The effect is more pronounced when streaming and not as severe when playing music from local files but still there. The FiiO KA3 might have the technicalities edge for electronic music and such genres or be better suited for ultimate detail and clarity lovers but the RU6 with its more natural timbre and grander soundstage is the obvious choice for classical and acoustic music. As on many competing dongles, this has been realised in the form of an additional op-amp (identical to the primary headphone output op-amp) as a unity gain amplifier. In contrast the KA3 is more extended, faster, with increased clarity and more detailed presentation but it sounds somewhat leaner while it can't touch the naturalness and physicality of the RU6.

The chrome striped sides, countersunk gold connectors and bronze text all contribute to an appealing old-school aesthetic. With easier to drive headphones this shouldn’t be a problem at all, but be aware that with more demanding ones you could have a little more mid-forward sound sig. To overcome distortion that comes with an amplified weak signal, the RU6 incoming bit-stream is fixed at full volume, with 9 sets of resistors and switching relays enabling a total of 99 steps of fine volume control within –6dB to 0dB on each resistor set. Digital Audio Bridge: convert DSD to PCM: convert all audio signals to left and right channel of 24 Bit/384kHz serial audio data signal.Unaltered and effortlessly articulated, the RU6 renders up-front vocal imaging and intimate midrange instrumental presentations with satisfactory resolving power. I meant it as I hear more difference in technical performance than overall tonality between these two. It has it's own Volume Control mechanism and is powerful enough to drive any IEM that I've tried so far. The bass is visceral, weighty but still tight and well controlled, fast, clearly defined and multi-layered.

And yet, it is such new technology that has breathed life into the old design and the first wave of products have proven to be surprisingly popular with discerning audiophiles. Understanding this issue, Cayin developed a fully analogue resistor array volume control circuit that provides 99 steps volume control through 9 segments of resistors and switching relays. Bass hits strong with a great authority, and I hear a deep sub-bass rumble; mids/vocals are clear and detailed, a bit more revealing; treble is crisp and clear, on a brighter side but with zero fatigue. This proved to be very useful as I am using my RU6 with anything from as high as 100db to as low as 91db of sensitivity listening devices with resistances up to 600 Ohm. This is not a matter of right or wrong, it's a matter of preferences and I can understand some listener prefer it that way.However I reckon that being Analogue it would probably mean RU6 will likely score terribly with measurements. Canpur is showing that they have come to do serious battle in the space, and these CP32E are no exception! I will not fall in so many details on headphones since I think the point is to explain how RU-6 enhances different replays but I will outline that RU-6 pairs well with Sony MDR-7510, CAL!