I've only had 1 krell product the kav 300il integrated and I loved it. The unit did run hot though and went in for service several times under warranty to get the amp repaired. Once the warranty was up and the amp baked itself again I used it as a preamp for several years.
I've been rebuilding my system since 2015 and all I know for sure is the speaker/amp combo really can't be judged separately because both influence each other enough (at these prices) to affect results. I could offer some examples, but I'm sure you guys already have had similar experiences.