Sound comes out of PC depneds on sound card inside PC . Most built in sound card are poor by audiophile standard. You can go as cheap as Chaintech AV-710($30 I think but don't be mislead by its low price) or as high as full blown studio qulity sound card. Audigy are praised a lot because it's one of the most popular soundcard but those Creative sound cards are nothing special. I have Ego U24 and it blows away Crystal chip built in sound card. Also RCA jack will be very unlikely increase sound fidelity over 1/8jack.