jeffreyw
The 800’s are very current hungry, earlier ones even more so, look more towards large "bi-polar" (Gryphon) integrated ’s they will give more current into those demanding loads, rather than large "mosfets" (Pass).
There are minima of 3.15 ohms at 91Hz, 3.1 ohms at 620Hz, and 3.67 ohms at 21kHz. Given that there are current-hungry combinations of 4 ohms and –52° electrical phase angle at 62Hz and 5.3 ohms and –39° phase angle at 8.6kHz
Cheers George