“The Berkeley Audio Design Alpha USB is a breakthrough product that not only overcomes the limitations of the USB interface, but provides a state-of-the-art method of getting audio out of a computer.”
—Robert Harley, The Absolute Sound, Issue 214
Click on the Alpha DAC Series 2 or 
Alpha USB images for more information
"The original Alpha DAC was a groundbreaking product, both in absolute performance and in its spectacular value. The Alpha DAC Series 2 is considerably better, and in musically significant ways." "The Alpha DAC Series 2 would have received my highest recommendation had it cost $15,000. Yes, it sounds that good. That it sells for $4995 qualifies as a minor miracle."
—Robert Harley, The Absolute Sound, AVguide.com, November 2011
“After four months using the Alpha USB, in combination with the Alpha DAC Series 2, I'm continually astonished by its level of performance. In fact, the Alpha USB is so good I've yet to hear a better digital interface. Period.
—Chris Connaker, The Computer  Audiophile,  March 2012