i use a firewire audiophile with a powerbook. it seems pretty good to me, except for one thing, i cant send my computer to sleep without without the thing crashing (i’m not sure wether its drivers or os x, but the audio stops and i have to restart). its very annoying. m audio have been little help, promising a fix in the new driver version, and failing to deliver it. also failing to respond to my emails. it does sound good when it works though!