anyone have any experience with Krell Amps humming

My Krell FPB 200 (I sold it a while back) hummed and I lifted to ground. Here is a simple way to check for a ground loop. Use an adapter plug, three prongs to two prongs. If you don’t have one around the house any supermarket will have one. If that does not work call the nice people at Krell.

Do you have the Krell plugged into an AC conditioner? If so, try
plugging it directly into the wall. Krell amps, like a lot of amps,
do not like to be plugged into an AC Conditioner and will hum
if plugged into one. Next, do you have all your gear plugged into
a 15 amp circuit that is not dedicated for your system? If so, your
amplifier may be starved for juice or picking up a hum from another
appliance in your home, or even from a neighbor's home. Way to
solve that is with dedicated properly grounded circuits with Hospital Grade outlets for your audio/visual gear. Put your amp
on a separate 20 amp circuit and a separate circuit for the AC Conditioner. If your AC Conditioner is also an isolator, you can
plug the rest of your gear into it. After installing dedicated circuits
all humming is gone, my system is dead quiet, sonics are improved and no more humming.

As it is a 5 channel amp, are all of the 5 channels being used? If so, are they all being fed balanced XLR or single ended RCA's?

The amp comes with grounding pins to insert into the balanced inputs that are not being used.

Give us some answers to our questions, especially the cheater plug and we can troubleshoot the issues with you.

Cheater plug did nothing to change it. All gear is in one circuit, but have had Bryston, Pass Labs, Sunfire and B&K in same circuit in previous few days with no hum. Using RCA's as interconnects, can see no pins inserted in XLR's and none were in box, there is only the small silver piece at each xlr, that I'm assuming is somehow related to the connection. Don't have a dedicated circuit to put it on for now. All other gear is being run through line conditioner, have tried amp both straight into wwall and into conditioner. Odd new facts, the mnore interconnects run into the pre/pro the more hum, and when my subwoofer is connected and powered up, hum is almost 80db. Very strange, as I said I've had multiple amps on this circuit and configuration this week, and absoutely zero noise.

You must have the pins if you are going to use the rca's or you will get hum. Did you buy this new? Krell sounds best balanced. The shorting pins go in pin 1 and pin 3.

Dave