SummerTime and Amp Heat

05-30-11: Willland
I too run a fan to draw heat from my B&K EX4420. My amp is the older model of your Ref2220. It draws 75 amps of current peak to peak .......

Noooooo! it does not draw 75A p-p all the time! The amp specs might say that it is capable of supplying 75A peak but the amp does not do that unless the load requires it. The 75A peak is just the max capability of the power supply transformer & capacitor bank to supply that much current.
it runs warmer to the touch 'cuz the bias is on high(er) side (to perhaps make it run longer in class-A before switching over to class-AB).

The links are to long to post. Just Google capacitor life shortened by heat.

see if you can find out what at temperature the specific B&K model is supposed to run - if possible. Then make sure that you are operating it under those specified conditions.
For ex, many of Pass' designs (specifically the older Thresholds) were meant to have their heatsinks at 52-54C. That was supposed to be normal operating conditions.
FWIW.

05-30-11: Hifihvn
The links are to long to post. Just Google capacitor life shortened by heat.

True Hifihvn that cap life is shortened very quickly by excessive heat BUT.............just because the heatsink is getting hot does *not* mean that the power supply caps are getting hot! Depends how the amp is made & where the power supply caps are w.r.t. the power transistors & heatsinks. The OP says that he's drawing heat out of the amp which presumably means heat from the power transistors only. The power supply caps could be very cool if the amp has grates on the top-plate, bottom-plate.
Cannot assume that power supply are automatically hot if the heatsink is hot.....

I agree with Bombaywalla. Heatsinks get hot because they are doing what they were intended to do.