Jeff:

I have installed input level controls on my amps that didn't originally have them except for the amp that drives my high frequency horns. On that amp, I lowered the gain to less than unity (an actual voltage loss!) by replacing the input tube with one which has lower gain.

When I calibrate the 950, I set it's trims at "0" for all channels and the main volume at "0". I then do all the level adjustment with the volume controls on the power amplifiers.

If I had to rely on the trim settings in the 950 with my efficient speakers, I would never be able to get anywhere close to 75db.