Haoleb,
Not to disagree with you, but the NAD models you mention are 2-channel stereo amps. The NAD stereo models have always been good into lower impedances. It's 5-channel and 7-channel receivers where amplifier cooling becomes a huge issue with lower impedances.
And it's the continuous power output with five channels driven that separates well-designed power supplies in receivers from cheaply engineered units. "Clipping" power can be measured in a short-term instantaneous burst (and the manufacturer will make those claims, sometimes calling it "dyamic peak power" into loads as low as 2 ohms) but after a few seconds, the receiver will go into current limiting or shut down. (Naturally, that is never mentioned in specifications!)
By the way, lots of old stereo amplifiers and receivers had no problem driving lower impedances.
Regards,
