Geoffcin is right about the Pioneer having a bit more power, though I would argue the real world impact this power has and it's weight in the decision process...at a $700 difference in price I think a better comparison would be the 52txi, wouldn't it? I think the 52txi still has more power than the 2400 and is about the same price as the 2500.

If you're really worried about power requirements at this level, you probably need external amplification anyway. I think Geoffcin would agree for the $700 difference in price between the two you'd be much further ahead to rely on external power amplification for 2 or 4 channels if this level of power is ever going to be required. This would allow you to cheapen up a bit on the size of receiver and just buy one the basis of it serving as a pre/pro.

I was at a demonstration at a hif-fi club meet in Dayton last year where they cranked out 8 watts into 5 channels in a 16 X 20 room on some Best Buy JBL's through a modest Denon receiver and acheived something well over 105 dB's sustained during a DTS test disc...Any of these receivers will go pretty damn loud without clipping or distorting at all and still allow 6-9 dB of headroom.

By the way, I've meant to ask this for awhile now, I think the seating area was not perfectly centered so you were probably 9 or 10 feet from the front wall...I'm 99% sure they used 8 watts through 89 dB efficient speakers...
Assuming a 9 foot distance from all 5 speakers, can anyone here do the math to tell me if these numbers add up? Isn't the rule something like +3 dB for every speaker added and -3 dB for every meter above 1m from the source? I seem to recall at the time their numbers were off a bit, but I didn't have my physics textbook with me...
Thanks.