@bartsw
@faustuss Below 20Hz, it’s about feeling it, not hearing it.
All types of audio amplification have a much wider frequency range than is specified in the McIntosh documentation. Essentially, the frequency response below 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. Likewise, the high frequency response being a wide band amplifier which the MCH300 is, the high frequency response is likely down by 3 dB at 100Khz which is ultrasonic and out of the range of human hearing.
The Mc’s bass can be boosted or cut 10 dB which will ameliorate or increase the -3 dB natural roll off in the amplifier’s frequency response. In addition, you can choose up to ten different hinge points between 40 Hz and 250 Hz to optimize your main speaker’s low frequency roll off to your subwoofer’s optimum crossover frequency. There are also main speaker settings for size including your front and satellite speakers, so they better integrate with your subwoofer’s crossover. There also LFE and digital signal processing that can be incorporated as well.
No simple rationalization as to the quality of products capabilities is really appropriate.
I forgot to add that the two subwoofer output channels are preamp level and the main amplifiers frequency response has no bearing on the subwoofer output preamps frequency response which isn't specified anyway.
