cooling my Krell monoblocks

Again, I urge caution.
ALL amps without fans as a designed in feature are passively cooled. The idea is that warm air rises and pulls cool air in from the bottom. Running under normal conditions in a 75f house, this should be enough. Stick kitty on top and finish the job by clogging it up with cat-hair and dust bunnies and you've got an overheating recipe.
Extreme use, like averaging about 1/3 power will stress SS to the max. Add a clog or 2 and there you go.
IF a fan is used, I don't think it should blow AT THE TOP of any gear. This will force air backwards down into the unit and restrict natural convection. Still air in the amp will just get hotter.
Many years ago I designed and built a small (4"box fan) that fit snugly on the back of my Carver Cube. It blew OUT, sucking air thru the amplifier. I could and did run it all day long just short of clipping without it cooking.
In general, I would say that pulling air up/out of an amp with internal heatsinks and pulling air over external heatsinks would be best.

I'll contact Krell and find out what options are available and let all of you know the reply. While I'm at it I can ask the D'Agostinos where the word "Krell" came from. That too would be interesting.

Try using fans to draw the heat away. I use Noctua fans - they are Swiss made computer case fans and the quietest around. The other brand would be Scythe, which are also quiet compared to most fans but a little noiser than the Noctua. At $20 a fan, it may be worth it.

Classicjazz - do you set the Noctuas on top of the amp to pull heat out of the inside or along side to pull heat from the fins?