How do I reduce the overall gain in my preamp ?

Hi Albert
Dweller's suggestion is definitely the best of the above. If you aren't able to follow the mod instructions for lack of technical know-how, a local repair shop should do this for you fairly inexpensively. Retain the mod instructions for future reversal in case you decide to sell it later on.
Or insert a quality passive attenuator into the tape loop, as an aside on Newbee's suggestion.

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

I have LS-2 that had gain reduced by dealer. There is a
jumper on the board that is replaced with a resistor. Gain
is reduced by 12 db I believe. Do not know where in circuit
they do this, contact dealer or ARC.

Thanks guys for your wonderful help!
I hope some of your tips will work for me.
Anyway, thanks again.
albert.