keeping amps cool?

I would only aim a fan at the cooling fins, unless I was certain the amp did not have a built in self bias scheme.
The Parasound HCA-3500, for instance, heats up appreciably until it reaches a set temperature.
We took the top cover off my friend's HCA-3500, to see if it would run cooler. It biased up even higher, with the cover off..

You will skew the setting even on a fixed bias amp.

Actually you're better off using the fan to draw heat from the amp instead of blowing air directly on it.

"Actually you're better off using the fan to draw heat from the amp instead of blowing air directly on it."

yes, I use a PQ exhaust fan...
http://www.hometheatercooling.com/purchase.html

Drawing the heat is easy. anyone else concur it's better than blowing filtered ionized air -gently--at the fins?
I believe in efficiency and know blowing is more efficient than drawing away.