If it's a ground loop hum there is a pretty easy fix. To test if it's a ground loop hum, put a cheater plug on the amp's plug and see if the hum goes away.
Any way to "improve" a Conrad Johnson MF 2500
I recently purchased a 10 year old CJ MF2500 amplifier. It is in perfect condition and it sounds excellent, but I noticed a hum coming from my speakers when it is turned on. It got me thinking, since there is no way to upgrade the power cord, if there was a way to "refurbish" or update the amp. I don't know if that is something normal for a solid state amp, but it's sounds so good and is in such good shape that I thought I would see what the rest of you thought. It would be nice to see it work for another ten years.