setting up a hometheater with power supply questions?

[JimJ 5,000+ posts]

Which is a plate amp or a rack amp ( I think that is what it is called, like the Beringer)

Yup. Rack amps have their own little quirks, like needing a seperate crossover as most of them don't come with one built in, and they may need mods to the fans to quiet them down. But once you get in the 600W range at low impedances, you can't beat them for value.