I have been extremely happy with the latest version (the Black label) of the Critical Mass Grand Master (GM) platforms. I have one under my CD player and two under the two monoblock amps. A fourth GM will arrive soon for my subwoofer amp. The level of realism, naturalness, musicality, and involvement the GMs added to my system is breath-taking. The huge improvement is over and above what I had already achieved with a variety of well-regarded (and expensive) isolation/damping devices which the GMs replaced.
The noise floor was lowered dramatically, resulting in a significant decrease of distortion. There is now much more perceived detail and more easily perceived nuance. Cleaner, clearer, crisper, purer sound; more focused images, better separation of instruments, deeper soundstage; greater extension at both ends of the frequency spectrum; improved macro- and micro-dynamics; quicker and crisper transients; improved coherence and PRAT; purer harmonic texture; etc. The bottom line for me was the significant enhancement of musicality and involvement.
The Grand Master is a sophisticated device that converts unwanted vibrations (airborne, component, structural, and its own) into heat. Joe Lavrencik, the brains behind the GM, was recently granted a patent for his devices. Very helpful. A true gentleman. The same can be said for his dealer Brent Rainwater of Rainwater Audio (843-665-6113).
On the practical side: The GM is transferable between components that are less than 130 lbs. (GMs for heavier components can be built.) So, your investment is less risky if you should change components. Also, you can "dial-it-in" for optimal isolation/damping, and customize it for your individual sonic preferences. There is built-in headroom and flexibility.
Disclaimer: I am not affiliated with Critical Mass or Rainwater Audio.