Welcome newbies!
I personally have two separate amps driving five speakers in my HTC. I also use a pre-processor rather than a receiver. Yes, I can indeed hear the difference which is most prominent at higher volume. I enjoy listening at higher volume so the investment is worthwhile for me! YMMV.
aarons your room is on the larger side so you may indeed benefit from increased amplifier power, unless you really don't play the system very loud. Bigduke6, is your listening room also large?
BTW, if you do decide to go with separate amps, you should likely consider upgrading to the "HP" version of the Axiom speakers. I also found this to be an improvement!
Enjoy!
