Here's a rather boring picture of my VPI's feet - I have to raise the back a little in order for the table to be flat (uneveness in the floor underneath):
So for years, I was simply adjusting the feet, as anyone would, by unscrewing them, and said feet would be a bit loose after a certain point. What is interesting about that picture are those shiny washers, which enable me to actually tighten the feet really hard and maintain the height I need. For years, I could not understand why the bass would be a little slow and fat, and the midrange a little smeared, at least when comparing to HDCD (e.g. the Janaki Debut). It was not as bad as some suspended turntables where I've heard the bass drum bloom follow literally half a second or more post impact, but still not right.
A simple test would provide the solution: crank up the preamp all the way - ~100dB gain - and hrds tap on the turntable base or platter; with the loose feet, there would be delayed feedback from the subwoofer as well as chaffing; once the feet were tightened, the feedback is gone. I don't know why it took me so long to realize this, but suffice it to say, I no longer care for suspended turntables. It is remarkable now how close the Janaki LP and HDCD sound, down to the drama of the shredded violin in one track. It is equally remarkable how detrimental micro-movements can apparently be.
Finally, FWIW, here are the Isodamp strips between the amp fins and the Noctua fan underneath.