D/L and run AIDA32. The actual maker has quit production and the name has change to Everest, i believe it is called, but the program can still be found at variuos locations.
http://www.majorgeeks.com/download181.html
Theres one. See if that can identify it.
If not, you will have to physically inspect the card. Look for silkscreened names on the card (if it is a card) or get the numbers off the larger chip on the card. If its onboard sound, will have to track it down by the motherboard name. AIDA will give you that for sure.