One small thing I can offer is that I was able to use this USB soundcard to drive a set of SPDIF speakers. It works great; 'perfect' sound quality: http://www.ebay.com/itm/HA-INFO-NG-C...item27be820192 I don't know how the DAC part of that chip is, but at least doing digital->digital works nicely. And it's plug and play for us.
Could you please elaborate on that last sentence (in bold) ? What software did you use to play the music ? Do you mean that no fiddling with ALSA and/or PA was needed ?...