I find this subject quite frustrating if not maddening. It would be easy to demonstrate whether or not vibration control is necessary or not with a variety of solid state components and yet... I've yet to see this happen. I mean, how hard is it to put a PA speaker in front of an amplifier and measure the effects, or lack thereof?
A long long time ago I owned a Radio Shack phono preamp. It literally rang like a bell. Probably due to cheap ceramic caps, but besides that singular piece of gear I've never heard this happen again nor have I seen it demonstrated in solid state gear. What if, for instance, vibration testing led to better component selection? Or what if we found out it doesn't matter below 150 dB? We may never know because any testing in this field has not become apparent.