diytube.com

OK, so what happened was I thought it would be better to use regulators for the 75 and 20 volts sources. I found out by pulling the jumper between the preamp and amp, when I did, it was silent. And I thought that 75 volts on one side of the output capacitor will make a thump, and it did. But if it came up slowly, it wouldn't. The way McIntosh engineered the regulator, it came up slowly and you only get a very slight bump.
Problem solved, by doing it the correct way.

Now the loudness does too much, and I have all weekend to screw it up and put it back.

Ok the 6100 has a Compensation switch that has a Loudness - Flat - and Presence setting. Flat is of course flat, loudness lifts the bass X 5 and Presence lifts the mids about 1.8 X. 5 times bass is too much, so I fixed it, now the loudness increases the bass 2.5 X and the treble 1.5 X. No other controls were affected. So it's done, and put back together.
Thank you Geek and everyone.
On to Philcos.

Rock & Roll, dude! Glad it worked out