I purchase this all in one DAC + Amp because I love the design and the interface it provide, very useful. But after get it, I found in order to make it sounds great, it need some hard working. I made a lot of experiments after purchasing it for 2 weeks. Here's some summary   Source  - Macbook Pro - Philips Desktop CD Player   Headphone - Sennheiser HD 700 - Sennheiser HD 650   Different Combination - Macbook Pro + Sound Blaster X7 + USB Digital In = Small noise from time to time  - Macbook Pro + Sound Blaster X7 + Optical Digital In +...

I have just brought the HD700 last week as my very fist HiFi headphone. Since it just have been burned-in like 50 hours, I can't really tell now.  It sounds amazing out of box, but when play some certain type of music like "Sovngarde" in "The Elder Scrolls V: Skyrim (Original Game Soundtrack)", it sounds very "unstable".  I will keep posting to see after couple hundred hours, will it be any difference