So I'm pretty set on getting a D4 mamba for my ultrasone hfi-780s but I had a few questions first: the d12 has coaxial and optical input/output... what are these for? do they offer better sound quality?
Another thing I'm wondering about is "amp pairing," specifically with the ultrasones. I'm assuming that amp pairing has to do with complimenting the strengths of the amp with the weaknesses of the headphone to increase the overall sound quality; is this accurate? I've read that the d4 has pretty smooth highs but I can't really get a feel as to whether or not they will make the hfi-780s' treble a little less harsh.
