Agree with Johnnyb53 regarding Herbie's tube dampeners. They're cheap and they work. I have them on all my preamp tubes. (For power tubes I prefer Pearl tube coolers, which dissipate heat well and should prolong tube life.)
My two-chassis Doshi Alaap preamp is inside a closed-door cabinet, so somewhat screened from airborne vibrations.
For isolation from the stand and dampening of internal vibrations I've tried:
Vibrapods
Stillpoints with/without Risers
Symposium Rollerblocks with:
- steel balls, not cryoed
- tungsten carbide balls, not cryoed
- steel balls, cryoed
- tunsten carbide balls, cryoed
For THIS preamp in THIS setup, the beneficial effects of each solution were as in the order stated above, the last solution being the best. Rollerblocks with cryoed tungsten carbide balls outperfrom Stillpoints under every component in my system except my TT (where Stillpoints + Risers + Inverted Risers are better and safer) and my universal disc player, where all these devices are a sonic detriment.
FYI, the benefits are noticeably greater from isolating the power supply chassis than from isolating the preamp itself. IME any component with large transformers benefits from isolation/dampening, e. g., my power amp and my Exact Power unit.