There is a large contingent of people who feel that Krell amplification tied to Dyanaudio speakers via Transparent cables is an excellent match. Even the small Dynaudios really like power - I'd go for at least 200w/c for either of the models you mention. Depending on your budget and your willingness to accomodate one of the heavy-duty Krells, you'll probably like the effects of having it on your sound (ie. the 250w/c monoblocks as opposed to the KAV-250).
There are others who think Krell is the most over-hyped piece of crap they've ever experienced. I have the KAV-250 driving the Contour 3.0's and would love to move up to the 250Mc's driving the Confidence 3 or 5's, so I'm not one of them.