Hmm, I should have checked back sooner after the last refresh. All my questions seem to have been answered--especially by Jerry's clear and detailed treatise.

So if I might paraphrase, the notch filter is really a parametric EQ control, with only negative gain settings.

It's really unclear from the panel layout and manual whether the single notch filter on the amp works on channel 1, channel 2, or both. An aggravation, especially if it doesn't work on the channel with the XLR input, since we all know most feedback comes from mikes.

Fortunately this amp has a separate 5-band EQ for each channel, so that should help somewhat.

Thanks everyone.
W-O