Bigger amps in an enclosed cabinet?

You can use a simple computer fan run off a wall-wort type converter. I use two with trade name "Stealth" and they are quiet to the degree that I never even notice that they are on unless I look or unless I check the on/off switch. They run 24/7, since my amp is on most of the time. One tip for quietness is to run the fans at a voltage somewhat lower than rated (e.g., if the fan is a 12V fan, run it at 6-9 volts). I purchased a variable voltage converter from Radio Shack and wired an in-line on/off switch. Also design openings in your enclosure so cool air is sucked in from the lower level of the enclosure and the warm air is blown out. Alternatively, you can simply point the fans to blow on the heat sinks of your amp, but still allow an opening above the amp for warm air to escape. On my cabinet, the openings are on the back where they cannot be seen, and cool air comes in from the space between the double doors in front, blows across the amp then out at a little higher level in the back. The fans really made a difference in temperature within the enclosure.