Lon,  I tried the Herbies last night and I'm not sure I like the new sound.  I think what I'm hearing is mainly the result of replacing Tenderfeet for isocups with supersonic hard balls under the Torii MK IV.  What I am hearing I would describe as clearer or what many here seem to describe as "Tighter" bass and low mid range frequencies or more "Micro detail" but for me the effect is less warmth, less low end impact/density and as a result, more high end energy comes through...more treble.  Which is exactly what I have been fighting to reduce recently.  I'm a little perplexed.  I'll remove the four isocups from the Torii tonight without other changes to see if I'm correct in thinking the isocup, super sonic hardball combo are responsible for the dramatic change.  Any input from others who have used these Herbies would helpful.  I think I'll copy this post to a new thread.  Mark.

PS...I also put 4 of the white large soft balss under my Turntable and 4 soft tenderfeet under the CSP3.  My ZP3 has always been underneath everything on a concrete floor covered with carpet and pad.

Mark, here is the page on the site for the Gemstones; I think his descriptions are accurate. The Jasper may also work well, I may have some of those in my toolbox too, I'll check this afternoon if you're interested in trying some.

http://herbiesaudiolab.net/isoball.htm

There were several other types, he's running out of these over the years.

I can see that this can be daunting. . . . It does change the sound and very noticeably and it will spark the urge to make adjustments if it reveals a signature you're not enjoying. In my case I think it revealed to me that the Decware interconnects were not the best fit for my system.
So you may wish to go back to Tenderfeet and avoid further changes. . . . . Though those further changes will bring you benefits in dynamics and soundstage I think.

What I mean about the location of the balls is. . . having them at the farthest corners seems to bring out the most low frequency sound, full and deep.

I hear you Mark, sounds like a good plan. Though I think it's more accurate to say "reveal" than "provide" when talking about the Iso-Cups. They aren't providing that brightness, it's coming from elsewhere.  I went further with cabling and isolation and power treatment etc. and I won't deny that at times, sometimes long stretches, it took away from the musical enjoyment. Luckily it also (at great expense) took me deeper into the reproduction and to a different level of interaction and enjoyment.

I believe Steve @ Herbie's says the supersonics are most neutral, and I agree in my experience. And it is not like isocups are particularly a wild card...many, many folks agree that they are very good at what they do with neutrality. So like Lon says, it is likely you hearing more of what your amp and the rest sounds like now. And since your experience with the cups is this profound, you likely have serious vibration issues that are worth pursuing in the long run.

But your past system tuning may not be right with the better resolution from distortion and noise reduction. I have had these struggles, but always found that once I adapted and made adjustments, the reduced noise and associated increase in articulation and clarification has been really good. Just have to bring it into balance.

And like Lon, tenderfeet under many things don't suit me for the same reasons...veiled, especially under heavy things like the Torii or P5 for some reason. Under smaller/lighter things they seem better, or even good. Though they sound better in the balance now, they are not likely the ultimate solution for Torii feet.

I found that we can pretty easily tune toward this or that tonal balance with room, tubes, cables, feet, etc, but if we can do this from within the foundation of each step bringing it all closer to reduced impediments like vibration, power and room issues, and equally, toward tonal neutrality, then everything tends to work better and without surprises...In this context, any adjustments can be better read and more easily refined toward deeper beauty.

All that in mind, I suggest trying a relatively methodical exploration. Maybe pull the feet from the turntable first to get everything but the Torii back where it was. Then, try to find the best sounding isocup placement from within the sound you have. This will probably be a good thing, but may not be just right in the context of having tuned your system without this level of vibration reduction with the associated tighter clarity.

Perhaps trying to fix the sound should be background for this, analytically going for the best tonal balance under these conditions. The bass and mid bass may be light, and the treble pronounced, but does the overall sound have everything else in balance...no masking and no accentuation??? The corners to me sound off balance, and four is better than three, but that could be different there, and if it seems a good starting place, just avoid touching the stock feet and see where it is best...a little forward or back...a little in from the feet along the front or back...bridging the gap of wood and base panel... an inch or two in toward the tubes. I find the pairs being symmetrical in the back, and in the front is good, but not being symmetrical front to back is better.

Here, the back two a little behind and outside the back corners of the back/outside transformers, and the front two are sort of between the front power tubes and the rectifiers. This makes some sense actually, sort of bridging the placement and weight of the transformers but also with the fronts in the middle of the tubes. I find that pushing the front feet a little further back and inside tends to be warmer, but if you methodically move them with symmetry, you may find something different and better for you.

Considering everything is different with better vibration management...speakers placed for the best sound before could well be a little or a lot different now. Perhaps by exploring for new sweet spots, the tighter, cleaner sound could be good if you can get your preferred balance bottom to top back with speaker placement...maybe play with ways to pull up the bass and mid bass without muddle.

You have several things I know of that can contribute to your high end exaggeration...starting with the Siemens EL34s. Though seductive, I can't listen to them without a fair bit of tuning. And Decware speaker cables and silver ICs do pull a lot upper-mids up, but leave the low mids and bottom a little soft and darkish in my experience. So they have some of what you want, but on top perhaps many things together contribute to upper-mid to high clarity, making one big problem. Also if you are using stock VRs and Rectifiers, they are pretty dry and clean relative to others.

Since you are wanting to keep the cables...and you are getting new power tubes that are quite warm and with less sizzle on top, depending on specific balance and synergy, this may be really good, I hope so. In the meantime, do you have other tubes to play with for now? Warmer VRs, inputs, or rectifiers.

If you have different power cables, cable rolling can help with refining synergy.

Have you explored tweeter resistors more?

Finally, maybe make a run through the Torii adjustments just for interest sake, and fine-tuning. They may be better different with reduced vibration distortions and noise.

So all this is about optimizing the feet and then tuning to the more revealing, less noisy sound.

My system/room seems less beat up by noise, and more inherently neutral/balanced and revealing these days. It can definitely sound weird, but with no part very far off...pushing the whole out of alignment so to speak... adjustments make sense,and problems can be more easily fixed. Everything shows up more, but the range of what is beautiful seems much wider, while gorgeous variations within this are easier to get.

So one way or another, one day or another, impediments like vibration seem worth solving to me.