In a few different threads I've been working on trying to solve a problem with my receiver going into protection mode at high volume. The receiver is rated at 8 or 6 ohms only and the KEF's were 4 ohm speakers. Since there was a general consensus that this was my problem I thought I'd get some Polk's to match my center speaker since they are rated at 8 ohm. This one member, "mazersteven" kept telling me that the Polk's wouldn't help since they are really 4 ohm not 8 ohm as the manufacturer states. As I stated a couple of posts back I bought a pair of the RTi8's last night from a local dealer in case I need to return them. I'm still not sure about the ohm thing but I have to be man enough to publicly admit that mazersteven was correct in that it did not solve the problem.
Being the stubborn person I am, I'm still leaning toward my own personal theory. My theory is that at the volume I like(about 70% of max), regardless of the ohms, when the part I'm listening to gets real loud and has a lot of bass, there is not enough overhead left for the spikes in wattage it pulls and the receiver goes into protection mode. If the ohms were higher the speaker would be less efficient and I would have the same problem at the same approximate real volume, IMO. OTOH, maybe it is just an ohm thing.
In case anyone has actually read this far, what I've done now is to set the crossover on the mains to 40 and it seems like I can get all the volume I need and I have a nice Velodyne sub anyway. I'm going to experiment around to see how I like the sound and also with my old KEF's to see which I like better when playing this way. If all else fails I may have to go the route mazersteven suggested and get some amps. I may actually be better off returning the speakers, getting the amps and hooking them up to my KEF's. So far I'm very happy with the sound of the Polk's for movies but I think I may have liked the way my KEF's sounded when listening to just music. Seemed a bit warmer to me if that is the correct term. OTOH, the Polk's are timbre matched when using the center channel and surrounds. I guess I'll be trying it out a few different ways.