I am gonna be buying a new imac and i want to hook it up to my 5.1 receiver via digi out so i was wondering what's the sound quality on the imacs were? Right now i have a soundblaster x-fi platinum connected via digi out to my receiver and was wondering if there's going to be any quality loss suffered when i hook the imac up instead.

If it is digital, you are not using the iMac sound circuit. It is your receiver that will do the work of making a sound out of it. I would not worry.

Thanks