They both seem to be surround receivers, so how do you have them connected, why do you need both for a pair of speakers or are you setting them up as two separate systems? If so, do they both hum?
What else have you connected to the receiver besides speakers, such as inputs, i.e. cd player, phono, TV receivers etc.?
If the Kenwood receivers had been working fine (actually he said " It worked perfectly in the other room with the same speaker setup) for 17 years and only started to hum since he moved them to another room, then I think they are not yet ready to make a trip to the recycling center yet.
I think as HD suggested:
This is a good idea just to make sure nothing has gone bad since he moved the two Kenwood units. Then we help him troubleshoot some more.