回複：Speakers have no channels. You use them as needed.

Speakers are rated by power and resistance.  Yamaha makes good receivers.  If you just want to have 5.1, you can get it from e-bay or local craiglist.  They should be very cheap as they are kind of obsolete.  If you want to play bluray, you probably want to go 7.1 channels or higher.

Good luck!  Merry Christmas and Happy New Year!

Alex