I'm helping with a musical in our small community, and I'm running the sound board. We have eight wireless mics hooked in and CD too. The soundboard goes from a mixed output (left/right channels mixed) to a mono equalizer (hence the mixed output) and from there to the amplifier. The cord from the equalizer to the amp is probably 25 feet. The signal is passed through the left channel into the right of the amp. Ok, so that's the basic setup.
Now, I had the amp set to a lower sensitivity as to avoid amplifying interference, and so I could see the levels on the sound board. Tonight I went to the musical practice, and a member of it had cranked the sensitivity to the max. Of course, to run it that way, my signal from the soundboard has to be smaller. And the level meters are of less use, and my sliders can't go up to far because it goes too loud. You get the picture.
So my question: what's better?: strong signal from the board/equalizer and less sensitivity on the amp? or weaker signal and more (or in our case, maxed) sensitivity?
And another question: what are good frequencies to drop on the EQ to avoid feedback? (FYI, the guy changing the settings thinks that the high sensitivity/weak signal decreases feedback.) (I think he's wrong, and it doesn't affect the feedback.)
And any tips for setting these things would be great.