Large brass devices on top of power amps ?

Most likely brass weights for Vibration damping.Vermontaudio.com sells a 3" brass damping disc..

Even though I am a fan of brass support BearPaws from edenSound and of Mapleshade's brass footers on their air dried maple board supported by isoblocks, any brass weight on top of amp or preamp leaves me cold.
The delicate harmonics are diminished leaving a more dynamic or forceful sound which is too stripped of shadings of sound character. Big and bold yet lacking subtlety.
Although this seems to be a minority opinion, keep in mind that the adding of damping weight should be tried with a return policy, just in case it is not preferred by you.

Listener57,
You raise an interesting point,is this theory or based on personal experince? is there some optimal weight/size that would dampen some component`s tendency to ring without harmonic supression? I agree that harmonic information is very vital and it`s absent is noticeable.

If you need to put weights on equipment to stop it from ringing,the equipment must not be designed very well.Just my opinion,nothing more.

Leave it to audiphiles to complicate a very simple concept. All the MASS is for is to dampen/reduce vibrations getting to the electronics. So use something that has a lot of mass (a baggie of lead shot comes to mind - don't eat/breathe it) and will couple well to the item it is sitting on.

You could even use a heavy statue or even a rock that has a flat broad base to accomplish the same thing. Dyna-mat type material or sorbothane will provide good coupling. Or just keep it simple and use felt.

Also, do what car audio enthusiasts do with stuff like dyna-mat to kill vibrations. You can line the inside of the chassis to accomplish this. Don't block the vents!

The use of small pucks and disks are for the psycho-acoustic crowd - they work great if you think they do.

And to think everyone said we shouldn't stack components;-)