If decoupling, and I mean competent decoupling, didn't work and and didn't keep most seismic type vibrations from getting up into the electronics then LIGO - long distance interferometer gravity wave observation - would not have been successful last year in detecting and observing gravity waves. LIGO would have done so a long time ago if it could but the sensitivity of the experiment required development of exceptionally robust isolation systems.
As has been pointed out already, resonant frequencies of cartridge, tonearm, platter of turntables as well as the resonant frequency of the laser assembly (spring mounted!) of CD players and the Fr of all the various electronic elements in components require relatively robust isolation devices, too. That's precisely why audiophiles discover that more expensive iso systems are superior to the usual DIY inner tubes and tennis balls. It's because their resonant frequencies are much lower and therefore more effective at 10-12Hz or wherever.
As has been pointed out already, resonant frequencies of cartridge, tonearm, platter of turntables as well as the resonant frequency of the laser assembly (spring mounted!) of CD players and the Fr of all the various electronic elements in components require relatively robust isolation devices, too. That's precisely why audiophiles discover that more expensive iso systems are superior to the usual DIY inner tubes and tennis balls. It's because their resonant frequencies are much lower and therefore more effective at 10-12Hz or wherever.