There are a lot of very knowledgeable people lurking around here. I was hoping to pluck someone with some experience inputing multichannel surround sound audio into the optical port of the iMac. Is it possible? If not, what about using a peripheral such as one of the very good Echo products (or anything for that matter - I just like Echo - super quiet, super accurate) which has an ADAT optical input option via TOSLINK. In a nutshell, What are the formats for multichannel surround sound and can the Mac input them?