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.
jeffatus
Is the hum coming from the speakers or the amp? The transformer in the 2500 does have a propensity to hum.If you placed the stone on top of the amp it is probably dampening the cover which in certain circumstances can amplify the hum.

Chuck
I'm late to this thread, but own both an MF 2500A, & a MF2250 ("non-A"). No hums with either. They're both very musical-sounding amps. I can't tell that the MF2500A sounds "better" than the non-A MF2250, except for the increase in power. And as I recall it's several hundred $$ for the upgrade....

I really enjoy my CJ MF2250A and it has no hum or noise.  Has anyone compared 

this amp or the MF2500A to the later MF2275SE / MF2550SE?