Today I received my DAC707 SuperPro digital to analog audio converter from Audio Magus.  I recently helped a friend set up his similar machine to use one of these devices.  It sounded really nice so I decided I should have one for myself.  It also frees me from having more junk in my PC as I had been using a Creative SoundBlaster Audigy2 ZS.  It was a solid card but I figured I could get better audio output by moving the conversion and pre-amplification outside the PC chassis which is traditionally full of electrical interference.  The SuperPro allows me to run either optical or spdif digital audio out to it for digital to analog conversion and then preamplification.  Anyway, it sounds great, but it was not immediately intuitive how to get my digital audio output working on my onboard sound card.

Here are a few tips so hopefully you can get SPDIF-out working with less hassle than it took me:

• The only volume level that matters is ‘PCM’ (at least on my particular onboard audio chipset).  I cannot access the ‘PCM’ volume level through Kmix, only through AlsaMixer (KMix 2.6.1 and AlsaMixer 1.0.15 BTW).
• Mute does matter on some channels such as ‘Master’, and ‘IEC958′.  Make sure these aren’t muted.
• Turn on crossfading in your music player because otherwise you might get annoying popping or crackling between tracks as the DAC seems to turn itself off and then back on between tracks if theres just silence.