This really looks like an instance where a high current outboard Amplifier would be the best choice. Something like a used Aragon 8008BB would really give you what you are looking for. Dual Mono construction, dual 1.2 kVA Toroidal Transformers, 140,000uf of Filter Capacitance, and made in America.
Here is a link for a review: http://www.hometheaterhifi.com/volum...gon8008bb.html
They usually sell on Audiogon for around 1200 Dollars, but sometimes are available for less. If looking to spend less, the 8008's predecessor the 4004,
is available for around 800 Dollars or less.
The 4004 was Designed by Krell Founder Dan D'Agostino and is very powerful as well.
Another good choice would be a Parasound HCA-3500 or HCA-2200. Both of these Amplifiers have large transformers and high levels of capacitance and were designed by John Curl.
If wanting to stick with an AVR, I would actually recommend the TX-SR876 B-Stock from Accessories4less. Bear in mind it weighs roughly the same amount as the 9 Channel 5007 and is a 7.1 AVR.
Here is a Bench Test of the TX-SR875: http://www.soundandvisionmag.com/rec...-receiver.html
It is available for 829, but again think you would be best served by purchasing an outboard Amplifier.
I am sure some will recommend Emotiva. While brand new is nice, I really think only the XPA-1 is on par with the 8008BB or HCA-3500 it terms of power and high current operation. The XPA-2 has a 1.2 kVA Toroidal Transformer and 60,000uf of Capacitance.