ARC LS2 gain reduction

ls2 is set to be stable at a certain gain deviation of such may result the circuit instability upto self-oscillations.

you may decrease the gain decreasing the values of the feedback resistors of an output stage or make it unity when you short the feedback path(using jumper instead)...
the DC supply may need to be revised for each feedback level used which dictates basically total circuitry redesign.

Contact ARC. A few years ago they sent me a fax with instructions. As I recall, it involved replacing one or two resistors per channel. So you need some soldering skills. I never made the change because the instructions said that the lower gain resulted in a deterioration of sound quality.

Dave

I had the LS2 - don't recall gain reduction
perhaps that was a fuse you wired into it
the LS5 does have a gain reduction switch
call Arc and they will help you out

Tom