Croft phonostage isolation advice needed

[paskinn]

I use a two-box Croft RIAA phonostage; the one with the phono circuit in one box, the power supply in the other. It's really excellent but, as some of you will know, the metal cases are pretty basic and rather resonant. At the price that's understandable.
My question is this, what is the best way of providing decent damping/isolation for these units? Any experience would be welcome. Thanks.

[daytona600]

heavy hardback book on the top to damp the top plate on the bottom depends on budget but rollersblocks or stillpoints work well on valve phonos