What about a fan blowing over McIntosh 7205 AMP?

If you're worried about dust getting into, use a fan dust filter. Can be found for cheap.

I have used those ultra quiet 120 mm PC fans to cool a number of power amps I own. I have cooled Parasound JC-1s and A21s by mounting the fan under the top cover plate, blowing out. These fans are so quiet you cannot hear them with your head right next to the amp. Took about 25C off the internal temp by doing this. They can be powered using the 12V turn on voltage supplied externally by the amps.

I don't care what anyone says, heat is the mortal enemy to long life of any electronic component. Particularly the electrolytic caps and solid state devices, whose lifetimes drop (and failure rate rises) exponentially with increases in temperature.

Authorized McIntosh Service Tech here, and I seem to recall that the MC7505 runs very cool like most recent McIntosh Solid State amps.
In my opinion your bias settings need to be looked at and I'd be willing to bet they are higher than the 13mV-15mV Factory setting. If I am right, you can then nix the fan once adjusted.

(I always reduce the bias by a schoshe [20%] to decrease heat/prolong component life).

Steve

Not sure about Macs, but Parasound amps always sound better with higher bias. Makes them Class A to a bit higher power level. Heating is a necessary evil, but high temps are not if you add external cooling.