The effects of vibration and tube amps

Thanks to both of you for your input! I'll check them out.

I'm using both products mentioned, and the result has been fabulous.

You might want to try with the ninety day home trial offer, a set of Herbies Audio Lab tube dampers, as well as a set of his proprietary material, inexpensive footers, such as Big Black Fat Dots (reminds me of that famous jelly ad: "with a name like Schmuckers, it has to be good"). Beneath the dots is your flat wood floor, wood plank, or marble/granite smooth tile. Some tonal seasoning to personal taste is possible.
Also, place these beneath your speakers -- crudely named footers can be wonderfully helpful at optimizing performance, without spending many dollars. Only $8.85 each, less than the sales tax on some other outstanding support ideas.
The herbiesaudiolab.com website is over-filled with variations on his vibration control products, and they really worked for me, even when the deeper bass output of transmission line loudspeaker physically close to tube amp.