Unfortunately, the MC7300 hasn't worked out as well as I hoped in this application. The subwoofer is a massive 12" dual 4 Ohm driver in a 6 cubic foot vented enclosure tuned to 20Hz. Before connecting the MC7300, I connected my impedance meter to each coil of the woofer and swept it from 20Hz to 80Hz, noting readings below 4 Ohms minimum per coil. Using the amp in stereo and the 4 Ohm taps, the sound is smooth and controlled - just as it was with the NAD.
I've been using it this way for the last two months. While it sounds excellent, the PG lamps flicker far too often. I hadn't taken the time to re-run the room EQ until today, given the change in furnishings. I popped in MI-5, selected Atmos, and played the opening scene. I had to continually reduce the level from what I'm accustomed to with the NAD to keep the PG lamp flashing reasonable. At one point the lamps were on continuously for seconds. Hmmm ...
So, the NAD went back into the system, I re-EQd the room, and the dynamic range returned. Next, I intend to try the 8 Ohm taps and I bet that levels the playing field. However, two other problems remain ...
1 - The left meter sticks. This is heat related and mechanical in nature.
2 - The amp will not come on automatically via my cool guy switched outlet box, which means the misses has to turn the switch OFF then ON to get bass.
The good news is that the amp sounds fabulous on my Altecs. I'll get it sorted.