how many channels?

I'm just starting to look at upgrading from a pretty good receiver to seperates. Since I have other expensive hobbies besides audio and video, I plan this use the same componets for music and home theater.

I have a Yamaha RXV-995 receiver I plan to use as a pre-amp. I've been looking at Parasound 5 channel and 3 channel amps.

The question is how many channels should I look for? Is 5 channels needed or should I look for a higher quality 3 channel?