Okay, assuming you have a usb cable connected between Desktop/Laptop what to do is this:
Go to synaptic package manager, download 'csound' and all the associated files/drivers with it. This will (or at least should) get you to the point where you can use the play/stop/forward/backward controls on the stereo to control the playback of the media program (most likely rhythymbox), use this as a check that the drivers are at least working
Next: go to system-> preferences-> sound-> OUTPUT TAB, and then choose a device for sound output, there should be 'internal audio analog stereo' (or something similar on a laptop) these are your built-in speakers or possibly the default soundcard if on a desktop system, this is set to be the default. Click the one below it - UAC3553B digital Stereo (IEC958), immediately after clicking the option, (if you are playing music/sound and have the stereo set to the pclink) you should hear your music playing.
Problem hopefully solved
1. (If not already set) On stereo -> pc-link, and make sure usb cable connected.
2. synaptic pac-man-> csound
3. sys -> pref -> sound -> Output Tab -> UAC3553B Digital Stero
4. Play music