1.
STOP READING MANUFACTURER SPECIFICATIONS!
2. Repeat
3. Once you are through with that, you have to understand that the specifications you are reading and quoting are 100% setup to trick you into spending your money foolishly.
4. For your money, there are far better products out there and I promise you my system which is only rated at 100 watts or so per channel will obliterate whatever you are seeing for a few hundred bucks.
5. As a matter of fact, when you see price go up, and wattage numbers come WAY down, then you are likely seeing far more realistic numbers for the quality and power output of the product you are buying.
For example, with this Onkyo system:
http://www.us.onkyo.com/model.cfm?m=HT-S790&p=s&class=Systems
You see 110 watts per channel as the rated power, but it is at a full .2% total harmonic distortion, and numbers are likely for single channels driven, not all channels at once (which is fine).
Whatever freakin' number 8,000w PMPO is I have never heard before but am sure it is just more marketing garbage which you are swallowing hook, line, and sinker. STOP IT! Even RMS wattage is likely rated at 10% THD instead of at sub 1% numbers (or lower) as they should be.
Denon, for example with this receiver:
http://usa.denon.com/ProductDetails/3038.asp
Also rates the power output at 110 watts per channel.
But! The total harmonic distortion (THD) at this level is rated at .05%
That is almost ten times better than the Onkoy and is likely on the order of 200 times (or more) better than the pieces you have looked at.
HONEST POWER? More likely 15 or 20 watts per channel. Maybe as high as 40 at sub 1% THD numbers with the products you listed.