Specs-wise, basically 6-8 ohms impedence and at least average efficiency (89+dB sens) works out very well in average rooms. If you can, spend much more (2X+) on speakers than the AVR, this matters a lot irt overall SQ. The speaker and sub threads have lots of suggestions for getting good SQ for a value price for various OEMs and models. If you will listen to 2 ch music a lot, I recommend some towers for FR/L with small passive woofers (5-6"). I would not invest in big woofers or powered woofers. Instead, you'll want a decent sub (again, see the sub threads-this is another several hundred $ well spent) which can certainly be from a different OEM but the the CC and surrounds should be timbre-matched ie from the same speaker line of the FR/L OEM.