According to "theory", a SS amp should "double down" as impedance is halved. To reverse this, as impedance is doubled, power output would be cut in half. In English, a 500 wpc amp @ 8 ohms SHOULD be a 1000 wpc amp @ 4 ohms and 2000 wpc @ 2 ohms, etc... As you know, the vast majority of power amps come nowhere close to doing stuff like this. It takes a MASSIVE power supply, very rugged output devices, a LOT of heatsinking, etc.... to achieve results like this. That is why the "big monsters" like Krell's, etc... that DO achieve results like this are both BIG and EXPENSIVE.
If what you say about the Bryston's is true, they are using some type of output transformer between the transistors and the speakers. While Mac has done things like this in the past, it is rather unorthodox with modern design technology. To my way of thinking, it would typically result in reduced bandwidth and a loss in overall sonic quality as compared to a similarly built "direct drive" amplifier. Then again, there are ways around just about anything if someone has the time and money to do the necessary research. Then again, maybe having an output transformer with various impedance taps ( like a tube amp ) actually GAVE them the sonics that they wanted. I guess it is something to check into. Sean