I have a new set of Mackie MR8 monitors and unfortunately there is too much internal component noise coming through the iMac 1/8 audio jack. So, now I am on a mission to find a good USB interface or sound card that I can bypass this with. I use the Firewire on the computer for external hard disks. It is a iMac i7 so I only have the one firewire port. =( I don't do any recording, this is for playback only. I've been searching over many threads and I can't seem to get a good opinion on a decent USB device that won't have driver issues and just give me clean playback.