can the mini feed into a home theater with 5.1 sound? If so, how?
Yes, the Mini can do 5.1, 6.1, 9.1 - whatever (see #3 below). But, that's provided the following criteria are met:
1. Your receiver has an optical input and is capable of decoding the digital surround file encoded in your media (e.g., Dolby Digital).
2. You have a Toslink cable between your Mini and the receiver.
3. You have media with digital surround sound encoded.
Number 3 is tricky. If you're talking about a DVD (real or ripped to your hard drive), then the Mini will work as is. If you're using another file type (e.g., MPEG-4 in any of its various formats), then you'll likely need Perian (free download) and a version of QuickTime that can passthrough the digital surround sound file. Apple seems to go out of its way to break passthrough. Not sure why, but my Mini home theater system is two versions behind the current because it can still passthrough Dolby Digital to my Onkyo receiver.