I am using this sound card with my X5000:
http://www.ebay.com.au/itm/Cmedia-Chips ... SwB09YIoMp
It's pretty cheap, and you get what you pay for. There seems to be some distortion sometimes, but fiddling with the levels in Sound Prefs sorts it. Also, I'm sometimes hearing a slight clicking sound even with no audio playing. Not entirely sure (I'm just plugging into the TV's built-in speaks), but it may not be stereo. And there's no pins to connect the case's HD Audio.
But apart from that it works.
Does anyone know if the Creative Blaster Audigy FX is compatible?
AmigaOne X5000 platform specific issues.