GScott has a ton of vinyl records and he'd like to listen to them again. How can he connect a record player to his AV receivers without disconnecting his home theater system? Optical out to the TV, and then use the composite connections? Leo says yes. You'll have a setting in your TV that turns on the optical audio option. The turntable he is getting will have a preamp in it as well as a USB to capture. Leo says that as long as the audio is balanced by a preamp, it'll work just fine.
What about bookshelf speakers? Leo says powered speakers will have a built-in amp and power. So that should be fine. The AV receiver will even work as a power source. Look at ELAC: they make very affordable, high-quality bookshelf speakers. Highly recommended by Leo.