2channel8 wrote,
"But seriously, folks. I am lucky that my speakers are sitting on concrete. They sound best that way. I’ve tried a few intermediaries. Wood platforms, steel points, stiff felt. None helped, most made no difference."
But have you compared the concrete stands to decoupling? While I suspect we all agree that different materials produce different sound, there seems to be a fairly wide difference of opinions regarding coupling vs decoupling (isolation). As Townshend points out, isolating the speakers has two benefits - isolating the speakers from the forces of seismic type vibration and isolating the rest if the system from mechanical feedback produced by the speakers.
2channel8 also wrote,
"My CD/SACD player does sound slightly better with sorbothane feet. Not so much that I’d be motivated to invest more. Am I missing out? Would a more expensive Isolation system improve the CD/SACD SQ more than the difference between sorbothane and nothing?"
Sorbothane is one of those materials that seems like a really good idea but in practice can do more harm than good inasmuch as Sorbothane, like a lot of soft or compliant materials like say rubber, even lead, stores energy and prevents it’s rapid exist from the system. CD/SACD players in my experience benefit greatly from isolation. One reason I suspect that’s true is that the laser assembly itself is mounted on a set of tiny springs and that laser assembly is therefore at the mercy of the resonant frequency of the springs, circa 8 Hz. Thus low frequency seismic vibration comes up from the floor into the CD/SACD player and excites the laser assembly, over stressing the laser servo feedback system. Of course there are many other reasons to disallow structural vibration from the CD/SACD player such as the circuit boards and their sensitive microprocessors on board. This is not to say that certain things in the CD/SACD player themselves cannot produce unwanted vibration as well, you know, things like capacitors and transformers.
cheers