I bought one of these for about $3 just for a lark and it works fine with AHI. I can then hook it up to my receiver although I haven't tested any music to see if it sounds any better than Paula.
I also managed to get my hands on a used Yamaha Cavit USB Soundboard. This also works with the Deneb. This machine also has a dsp and I was wondering if this dsp could be used to play mp3s instead of the cpu. An MHI driver perhaps?