best amp platform/stand under VAC Renaissance 30/30 300b amp?

Use your current rack, but place the amp on a Starsound amp stand. They are amazing, and you will hear a positive improvement. 

Check out butcherblockacoustics.com
New line just debuted at T.H.E. Show Newport 2018.
Highest quality at very affordable prices. 

Thanks. A friend also just sent me this, which is interestinghttp://www.theaudiobeat.com/blog/ikea_aptitlig.htm

There are or were several Ikea products that worked very well as component stands. I remember reading about them many years ago, unfortunately I don't know if the products are still made.

There are companies online selling maple butcher blocks made to your specifications. And at very reasonable prices too! I bought one custom- made for my TT's! For your amps you can't go wrong this way!

I use the following Mapleshade "maple platform with isoblock suspension" under my VAC Renaissance 70/70 MkIII amplifier, on a bare wood floor. Seems to do the job, as evidenced in part by the absence of any audible response to nearby footfalls:

http://shop.mapleshadestore.com/21-x-19-x-4-Finished-Maple-Platform-With-Isoblock-Suspension/product...

Regards,
-- Al

As roxy said, look into Star Sound Technologies. I was introduced to Robert at AXPONA this year and he brought some platforms to put under my amp and speakers. The differences were NOT subtle and they were definitely for the better. I liked them so much I agreed to work with him and now he is my sole rack and platform guy.

His designs are for redirecting energy to the ground instead of ’eliminating’ them. You will never eliminate them, rather you will change the resonance of whatever you put your gear on (an audible change).

Silent Running Audio
SRA
Customized to your component 

I have owned various cones (including ceramic), Mapleshade Isos (single and double), Walker Audio Brass Cones with nipples, Stillpoints with Risers,  none compare to Machina Dynamic HD Springs, which isolate vibrations in all 3 dimensions, AND they're very inexpensive. I have them under everything, including my Core Power 1800