What to put under my VAC AMP/ PREAMP??

Sistrum stand, stillpoints

Shun Mook GDR's are the best under my VAC PHI 300.1

How many do you use and where do you place them under your 300.1?

Hello Arthur;
GDR,' come in pack of three and one goes on the back, two at front.
Kevin from VAC modified bottom plate of my 300.1 so with little difficulties (cut outs for ventilation), I am still available to use Shun Mook.
Nothing in my personal experience comes close to these devises.
Harmonix is also good but not as natural sounding as GDR.
Shoot me an email, so I can provide you with photos and links to Shun Mook application.
P.S. Did you experience with different KT88's or perhaps some NOS 6550's?

Regards