I inherited 4 large 1980's floor standing speakers. I couldn't use them unless I had a receiver to drive them. I went on ebay and picked up a Sony STR-DG800 for $44 (it had a broken knob). It worked well at first. I then started to notice how hot this thing got. It could literally make my breakfast. So I got the idea that I should add some fans on this to circulate some air in there. It was already a perfect form factor to be modded anyways with all of the holes. So I opened it up to see what the insides look like and how much space I was given.
Once this thing was open, I saw that I had plenty of room and that this thing was asking for a few 120mm fans on top of the massive heat sink. The massive transformer on the left side was crazy hot and burned the skin upon contact. I had a spare cpu cooler and thought this would be the perfect time to use it. I aligned the fans to see what it would look like.
I pulled out the multimeter to find some 12v power. Most of the pins were labeled on the back of the pcb's. I found a bunch of 15v. The multimeter said these 15v powers were actually pushing 13v, so I used those. I cut and soldered the fans onto the power sources. There was 1 power source on each side of the receiver.
Now for the transformer heat problem. There wasn't enough room for the cpu cooler. So I took the top of the receiver and dremeled a hole for it to stick out of the top some. The top of the transformer had some tape stuff on it, so I peeled it off. Underneath there was some glue like stuff that was too hard to remove. I said screw it and put thermal paste (TX-2) on the bottom of the hsf and mounted it.
None of the fans are secured. The 2x 120mm fans don't have much room to move around. The only problem might be the cpu fan, but I don't touch it so it doesn't matter to me.
The outcome of this was great. This thing is very cool. It would have been quiet but the black 120mm fan is a high cfm fan, so it makes some noise. The other fans are silent.
Here is some funnies because I couldn't figure out how to get sound from my Acer Revo to the receiver. The only way I could at the time was to go from the head phone jack on the Revo to the receiver. I had a perfect cord to do this, but for some reason it seemed too small for the hole. So I found an extension cable and soldered them together. It provided sound, not the best, but bearable.
I have since fixed the problem with a composite cable from the TV to the receiver. I was surprised how well the 1980's floor standing speakers sounded. They are pretty crisp at high volumes.
edit: I now know why the receiver got so hot. It was because the receiver had an impedance of 8 ohms, and 2 of the speakers I was using were rated at 4 ohms.