I'd rather see it straight from THX themselves, but ....
"When it comes to amplification, continuous output tests are run on up to one, four, and five channels (simultaneously) of an Ultra product, but only one at a time on Select. With all products, the dynamic amplifier tests are done on up to all available channels. Ultra amplifiers must be stable on all channels to 3.2 ohms and swing an 18A peak, while Select products must be stable into 4 ohms (front channel) and 8 ohms (surrounds), and swing peaks of 12.5A and 6.2A respectively."
http://www.hometheaterhifi.com/volume_13_1/feature-article-thx-1-2006-part-4.html I've never felt that a THX certification really meant anything other than the manufacturer had sent a check to George Lucas. I mean, yay, another badge for the front of the gear, but I don't buy something just on the basis of being THX certified. There's a ton of fantastic audio gear that isn't THX certified. Axiom speakers, for example. Technically speaking, you're breaking the 'THX chain' by using them.
There are several members here with newer Pioneer Elite AVR's that have no problems running M80's, even though Pioneer still insists that 6-ohm speakers are the lowest their AVR's will drive.
I pay attention to this because I am one who has had problems with M80's and a Pioneer Elite. My old VSX-43TX (2001 model) can't drive my M80's at high volume before starting to clip. Which is why I drive my system with an Emotiva LPA-1 amp.
