[size=small]As far as I can tell internally the V281 is not fully balanced. So even if you use balanced inputs the signal gets converted to single ended, and only after the volume control it is split again for the power stage. Connecting DAC using XLR input may give you the benefit of noise cancellation, but if you have a noise free RCA connection it would make no difference.[/size]
True. I was referring to the balanced output on the DAC side. The Anedio is not all that different between SE and balanced out but some DACs sound quite a bit better from their XLR outputs compared to their SE.
For the balanced amp discussion - it's important to realize that there's different schools of thought about what constitutes a "balanced amp".
*As has already been somewhat discussed, the Bryston BHA-1 has "true" balanced input and outputs (including a 4-gang volume pot) but still converts the signal to single-ended along the way (for reasons which elude me).
*The Violectric V281 and the Auralic Taurus both use a vaguely similar setup in that they have a 2-channel volume pot in the chain. So for the V281 and Taurus it's more about using the pair of (internal) amps to drive your headphones which increased voltage swing and current delivery. This method is good for maximum input/output flexibility - any input can play through any output regardless of type.
*The Woo WA22 is marketed as a "true" balanced amp but internally we see only 3 wires going to the headphone jacks - thus it is not really balanced, and the XLR is just for convenience only. Same deal with XLR on the Yulong A18 (they don't advertise it as being fully balanced).
*There ARE some amps we might call "true" balanced. They don't even have to be all that expensive. The Schiit Mjolnir, the Yulong A28, and the Firestone Bobby all have separate signal paths for the left and right channels, including the 4-gang volume pot. They convert SE inputs to balanced (using a phase splitter). The Schiit is limited to balanced outputs only, while the Yulong and Firestone both provide 1/4" jacks - but using those is essentially like using only half of the amp.
*Then there's the rather new concept of a "balanced" setup using dual headphone amps - such as the Questyle CMA800R or the Nuforce HA200. The concept is essentially the same but instead of having two internal amps with a balanced signal path, they take things even farther by splitting the entire thing into a separate chassis. So the 4-gang volume pot then becomes a pair of stereo pots, and each channel even gets its own dedicated power supply.
As you can see, there are different ideas floating around regarding what exactly makes a "balanced headphone amp". Most of these designs have at least some merit, and really the only thing I object to is when Woo calls their model a "true" balanced amp when it really isn't. In my mind that's different from Violectric saying "4 (internal) amplifiers for true balanced output". It may be a technicality, but one of those statements is true while the other isn't.
