Well that was an interesting hour or so.
I followed AfterDark's lead in applying Dynamat Xtreme to a couple of OCXO containing devices - my SW-8 switch (pictured) and my OCK-1. Xtreme is butyl rubber - supposedly a patented formulation - with a heavy foil face. It is extremely tacky but is non-destructively removable from hifi gear metal cases... so far. Even after AB'ing which means, yes, sticking it down then peeling off for the comparative. Multiple times. The things we do.
NOTE: for this initial experimentation I just stuck it on the top cover for ease of access. For permanent use I'd move it to either/both under the top cover or under the base, neither would be visible.
I started with the OCK-1. I used a mixed female vocals and piano acoustic track. The damping brought clearly audible benefits - piano notes had more body, texture, richer harmonics and longer decay. They were simply put, sweeter and more realistic. Vocals had greater emotion as you could hear more of the very subtle breath sounds only just picked up by the mic as the vocalist placed more emphasis on certain words or syllables.
Inspired by this success I tried with my R26. Perhaps a slight improvement but not dramatic and it was getting a bit late so I couldn't be fussed AB'ing to check. I was about to call it a day for the evening then it occurred to me I ought to do a quick try with my other device with an OCXO. Well sure enough the SW-8 responded much like the OCK-1, with additive benefits of similar character, but most noticeable was a greater sense of acoustic space with richer, more layered and longer decay.
So some pretty satisfying improvements for very little cost. To be continued...