well i plug a audio cable from pc to amp not sure if its RCA

Do the connectors look like this?

http://en.wikipedia.org/wiki/RCA_connector

yes 2 connect to the amp and one wire connects to the pc.

Yeah, in that case I'd suggest the 2496, although you'll need a plain RCA to RCA cable, rather than the one you have at the moment.

Thanks for all your help before i decide to buy a new comp i will give you a full list of components . Thank you once again