I could use some advice. My NR509 says that it will do 6.1 or 7.1 surround, but to do that, I would need to connect an amplifier to the pre-outs and run those speaker(s) from that amplifier (if I understand it correctly). I've never used a separate amplifier, just receivers.
So can somebody expand a bit on what I need, and perhaps a recommendation on what to get? I'm guessing that since all I'm really looking for is something to power 1 or 2 surround back speakersspeakers, I don't really need something high end or really powerful. I'd need an amplifier with pre-out inputs? And connections for at least 2 speakers, of course.

The NR509 is an 80 watt receiver, I believe.
Thanks in advance