I am a user of 0404 USB. There is some opinion:
The headpohne jack in 0404 usb is quite good in this price range. I use this compare with CEC HD53R V8, it only weak in some bass (Using HD650). Sometimes I really think it is more detials then HD53R V8 (Using K701)......
Besides, I think U mostly use it as a Computer Sound Card more than a DAC. In some reviews, the DAC function chip is very good and used it in some HKD$2000 DAC. So don't worry about the DAC function.
Also, the 0404 USB have optical and coaxial input/output, if u want to connect to some RCA Amp, just simply use a Mini 3.5mm--->RCA cable. This It..............enjoy.
There is some woundful reviews, pls have a look.
http://www.digit-life.com/articles2/pro ... 4-usb.html