Hi Bruce. It was tube amps that got me playing with vibration control 20 years ago. For the same reasons you mentioned. Glad to know you're gear doesn't go through tubes, too.
Wayne, it still doesn't make a lot of sense to me as to why this has an effect on solid state gear but it's clearly audible. It's also cheap and reversible so there's not much to dislike.
John, I am enjoying the 4's. There have been several changes, shower pan liner included, that keep making things better. I'll post about the adventure in existing threads but they sound great and continue to improve.
Have you made any progress with the 7pi bass bins? It would be nice to know how they compare to the front facing bass bins.
Building the Whammy was just an itch to build something. Opamp upgrades helped it a lot (and evidently there are even better ones out there), but no, it isn't a tube preamp.
I've no doubt the Oddwatt stuff sounds great. They had a room at the Lone Star show for several years and it was a great sounding room. They also had some of their gear in the Pi room and it sounded great in there, too.