How do I reduce the overall gain in my preamp ?

I would not try to modify your preamp.

I would look at getting a different preamp or look at getting a source that outputs less. Or look at getting speakers that are less sensative.

Just my 2c.

KF

Marakanetz, you can do it as you state with a less sensitive amp OR speakers. Going from 95db sensitive speakers to say 92db speakers will give your system less overall gain/volume.

KF