for the love of god, help!

[myfilthyheart]

my intel imac has a POS sound card in it. constantly crackles and makes weird ass noises.. i googled it, and it seems to be a trend going around with the new aluminum imacs.. anyway, to resolve this, ive been using my virus as my sound card. now, all of a sudden i have no audio coming out of my virus, unless thru logic. ive selected the virus as my output in the os.. and when i press play in itunes, the track refuses to play. videos online, youtube shit like that.. are choppy as hell, with no sound. if i swap back to the imacs output, everything works fine. itunes plays fine, the videos on youtube run smooth, with sound. but the sound crackles like crazy, and its annoying as hell. is this a problem with teh virus or the imac?