The Roland Quad Capture 2X2 comes from the world of pro audio but is a viable option when used as a USB DAC with a laptop or desktop. The Roland uses regenerated USB power, which effectively isolates the signal path from stray noise, a serious issue when DACs are used with computers. The unit is 100% USB bus powered.
The Quad Capture is usable without drivers, plug it in and it shows up as a 16/44 audio interface. This is all that's needed for CD audio playback, and all of the unit's enviable qualities are self-evident. Adding ASIO to the mix elevates the unit into the upper echelon of USB DACs, namely it enables bitrates up to 24/192. When it comes to "affordable" pro gear, I've owned a couple of Focusrite Scarlett units, and a Motu Traveler. I've used Mackie and Alesis USB mixers. I've tried out the latest/greatest soundcards from Creative and Asus. The Roland trumps them all with it's well-built chassis, and a noteworthy, buttery delivery of deep bass.
Rendering refined detail is Quad Capture's strongest suit, music is output with a smooth ease that I've come to associate with high-end DACs intended for use with home stereos, without a hint of the granularity produced by lesser units. The headphone amp appears more than capable of driving a finicky pair of cans, in my case a pair of AKG 701s. Currently, the Quad Capture is breaking in my new pair of Monster Inspiration headphones, I'll reach 30 hours sometime after lunch today, I'm psyched to hear the results.
I doubt I would have picked up the Roland at it's street price of $269—but I found it on clearance for $135 and at that price it is a steal. Value rating is based on price paid.
The Quad-Capture is the core of my portable studio