Isolation platform for the power amps

Butcher block is OK if done right. A big factor is how the butcher block is mounted and how the component is mounted on the butcher block. Not to mention what the butcher block is mounted on.

But there really is no substitute for real (rpt real) isolation which means, of course, mass-on-spring devices. Mass per se is good in the sense of inertia (i.e., resistance to external forces) and for mass-on-spring devices for which mass per se lowers resonant frequency Fr of the iso device, thus improving isolation effectiveness. The thicker the butcher block the better the system resist bending forces since it's stiffer. That would explain the populaity of 3-inch thick butcher blocks. Finally, the best results will be obtained by careful decoupling and coupling techniques, since both are necessary.

The coupling/decoupling sequence seems to be generally overlooked. Even "as" a sequence. Doesn't anyone else here measure? Or at least try it and listen!

Decoupling and coupling is not rocket science. The coupling is for draining off medium and high frequency induced or residual vibration from the component/system. The decoupling is for attenuating very low frequency seismic type vibration transmitted from the floor to the component. Since no single mass on spring layer is a perfect isolator (i.e., low pass filter) you can cheat a little by building two mass-on-spring layers, separated in resonant frequency Fr so they won’t interfere with each other. This usually means using high mass in the construction of the dual layer stack - e.g., slabs of granite or bluestone.The high mass ensures a very low resonant frequency for the bottom layer. Then the top layer is a snap.

Hee hee, I never said it "was", rocket science. Yet I don't see it often enough. But you can also use the high mass layers as differentially sequenced frequency attenuators by utilizing different strata's with their own specific characteristics. Unless you just "Really, really", like rocks, granite ect... Me? I like shiny things.

If using sequenced high mass layers was effective I’m pretty sure the LIGO project to detect gravity waves would have used them. What they did use, in fact, was sequenced mass on spring layers. The advantage to bluestone and granite for DIY audiophiles is low cost and effectiveness, due to high mass and stiffness. That’s why the big boys like Newport and other isolation platform manufacturers use large granite slabs for the top plate of their larger isolation platforms. Very low frequency seismic type vibrations, the most harmful ones, the ones that excite 😛 turntable natural frequencies circa 10 Hz to 15 Hz cannot (rpt cannot) be addressed without mechanical low pass filters of some sort. Performance of mass on spring systems is all about high mass and low spring rate. It’s rocket science.