Tascam US-125M USB

The Tascam US-125M USB mixer works fine as DAC in Runeaudio. Manual volume control for headphones and line out:

http://www.thomann.de/gb/tascam_us125m.htm

It has a Texas Instruments PCM2900B Audio CODEC.

Here you can take a look inside of the DAC: http://www.ipernity.com/doc/708643/album/640983