I’m assuming your ARC pre-amp has a PC board type Alps. The TKD, which is waaay better than the Alps will fit the space but has solder tabs, not PCB hookage. I don't know if any of the others mentioned here or my personal fave Taiwan 28 step ladder attenuator for $25 bucks will fit.
I made that very installation some years ago in an LS--1; it required soldering short lengths of 28ga. solid core to the TKD then shoe-horning them into the PCB eyelets. Quite challenging. That plus getting rid of all the by-pass caps made a wonderful sounding unit.
I made that very installation some years ago in an LS--1; it required soldering short lengths of 28ga. solid core to the TKD then shoe-horning them into the PCB eyelets. Quite challenging. That plus getting rid of all the by-pass caps made a wonderful sounding unit.