I personally like the ROTEL RB1091 monoblock, which was measured to produce 630 watts RMS/8 ohms, 1200 watts RMS/4 ohms, & 1580 watts RMS/2 ohms.
At what distortion rating....
That is the exact same module that Wyred4Sound, D-Sonic, Bel Canto, Jeff Roland (the list goes one and on) uses and they are conservatively rated..... roughly 525w for each module. Why pay more for the same thing. IMO
If you do your homework you will learn that all of these amps are running the B&O IcePower ASP modules, and they come in 250w and 125w versions as well.
That is the reason I went with the D-Sonic and Wyred units, they put them all in a nice package that puts out tons of power, stays nice and clean and barely warm to the touch, all the while being very efficient, meaning they don't trade power for heat...
I won't tell someone what amp to buy, just to look into what they are intending to buy... Both the D-Sonic and Wyred4Sound amp threads over at AVS are very informative about the Technology if some is interested in learning about IcePower...