20Hz rolls off a specific rate for that amplifier of say 3 dB per octave meaning the response would be down 3 dB at 10 Hz
Thanks for the info but that's what I wanted McIntosh to confirm but they didn't.
The Mc’s bass can be boosted
I know but if the rolloff is steep, boosting in by 12dB won't do much if anything. That's also the limitation I run into above 15Hz when I measure the room. Although it can't be heard, I wanted to test the speakers but the AVR was the weak link. Boosting 16kHz doesn't really do much if anything.
the two subwoofer output channels are preamp level and the main amplifiers frequency response has no bearing on the subwoofer output preamps frequency response
Good point if true. I use speaker level because 1. it's a lot easier to calibrate every speaker as full range and 2. I don't have to waste $1200 for archaic bass management software and processes, not to mention the hardware.

