Hello, I use the Nuforce ICON-UDAC2 amplifier, the sound quality is Exceptional and you can adjust the sampling rate to 96K through Windows 7 settings, the only con is that you can only connect it through USB terminal as input signal. It's a very small amplifier and the image in Amazon give you...

I prefer the Beyerdynamic DT990 Pro Headphones, they are cheaper in price, almost half the price of the premium.

I prefer the Beyerdynamic DT990 Pro Headphones, they are cheaper in price, almost half the price of the premium.

I own the Beyerdynamic DT 900 Pro from 2 weeks and never experienced that fidelity and exceptional sound quality in my life, balanced sound, no boost for Bass, but take care as these headphones hurt your ears if you boost it and hear it loud. They are Hand made headphones, robust construction...