I am shopping for some replacement speakers and had a question about speaker impedence. I have a Denon AVR-1910 receiver and I am looking at the Axiom M60 floorstanding, VP150 center, and QS8 surround speakers which are rated at 8, 6, and 6 ohms, respectively. Is mixing speaker impedence like this not recommended? According to the manual, speakers with 6-16 ohm impedence should be used although the Denon site states that 4 ohm speakers can be used. If the speaker impedence needs to be match on all channels, it seems that would limit the scope of my speaker selection. If it's ok to mix speakers, do they need to be close, i.e. 6 and 8 ohm vs 4 and 8 ohm? I'm guessing that it would be ok to mix impedence but wanted to get input from the experts on this forum.