Caps need to be replaced in anything after time, Krell doesn't need more work than anyone else, and I have been to the factory to help a friend drop off his entire Krell system for upgrades and stuff. The people there were great, and provided us with a nice little tour.
I have heard a number of their amps, starting with thefirst 50wpc unit, a few of their KMA models and two FPB models. The one I preferred the most was the FPB 700cx. This is a lot bigger than you want, but the FPB 300cx should be a really good amp for you.
The newer FPB series amps sound much less Krell and much more neutral and musical than the KSA, KMA, etc, models. IMO.