cones under your tube amps??

Once I had a trio of the Racing cones, under a SS amp, I think the set was to make the sound more tubey like. For sure, they did gave me a slamm that I have not since experienced in any other set up. In your case, the Racing Cones to stiffen up the bass would be ideal.

In any case, not all those moving type of points or isolators have the same good effect....the Final Labs Daruma 3IIs, made my DNA 225 sound not too slammy like the racing cones.

I would expect that a Promethean Base from Machina Dynamica would do a better job, but roller bearings under tube amps work well.

I use BDR cones #4's under my tube preamps with very positive improvements in all areas.

I use Sistrum platforms under my amp and preamp, and Audiopoints under my phono step-up transformer. They work very well for me.

Disclaimer: I work for a comapany that makes vibration transfer products.

I second BDR, a combination of (1)#3 and (2)#4 worked well for me under my VAC 160 Mono's.