Berkeley Audio Design Alpha USB

If you use a USB interface to play your music, and you want reference-quality sound, this little box is one of the few paths to get you there. Robert Harley wrote in The Absolute Sound, "I’ve tried the Alpha USB with many other brands of DACs, and it has always resulted in a significant sonic improvement over using the DAC’s integral USB input. In some cases, the Alpha USB has completely transformed the sound of a DAC, even a very expensive one."  

I used this Alpha USB between my Mac Mini and my Benchmark DAC2 HGC, and later my Berkeley Alpha DAC Reference, and my experience parallels Harley's--with the Alpha USB there is a wider soundstage, more secure placement of voices, greater sense of silence between notes and voices, and more air in the rendering. It holds true for either the SPDIF or the AES output to your DAC.    

I am selling this unit because I have transitioned from USB to a network interface (and had to spend nearly $5000 to get a network interface that sounds as good as this USB interface). The unit is in excellent shape, with no blemishes that I can see.  
 
Berkeley's product description is here: http://www.berkeleyaudiodesign.com/alpha-usb/
Harley's original review is here: http://www.theabsolutesound.com/articles/berkeley-audio-design-alpha-usb-interface/