The question is: do you defeat the function of isolation devices if you put felt pads under themto protect the floors and make the speakers easier to move?. Will this insulator pad stop the function of the isolation device?
Easy solution. Just listen. Get used to the sound with the felt. In a few days remove it to compare. Doing an A/B comparison right away doesn’t work as well.
Horrible solution. Where would this website be if people tried and listened instead of wildly guessing and pontificating? Don't listen to this wild man. Keep posting and asking until you find the one saying what you already decided to do anyway, and then do that, but under no circumstances actually compare by listening. Once you start down that road no telling where it leads.
Felt would change the perceived sonic outcome of the use of the given isolation device.
If the change is enough to alter the characteristics enough for the individual involved, or not? That is the question.
All one can do is try. Try one, try the other and then try both at the same time, listening to the differences between the three states.
After the given switch is made, wait a few weeks or days and make a swap or change.
Our ear-brain, like our eyes, builds up the image over time. In this case, it is a sonic image, built up, over time.
Which is why a-b switching in audio is just plain wrong. It’s about the cumulative effect on subtleties, it’s not about the gross levels of anything.
Subtleties, all subtleties. And that takes time to realize. Exactly like that of intelligence, exactly akin to it neurologically, it’s a difference and time thing. Speed, rate, and breadth of cognition, as a differential between individuals.
Some can hear it in seconds, some can hear it only in days or weeks. Some can’t understand it at all. And probably never will.
Most people, when asking a question, don’t understand the nature of the question. To compound the nightmare, most people are not trained to properly frame or put together a question. They just don't have the disciple and rarely encounter a need for it.
If a question is properly fleshed out, it generally begets the answer. No need to post a question as a thread.
The two are a matched pair, a set of bookends. Question = Answer.
the OP was not properly fleshed out, so no one could, relatively speaking, provide and answer that was any better.
and you end up with a thread, where people walk past and talk past one another...
Which is, again... invariably the essence of audio threads.
("Why does the sun shine? Are Stars just pinholes in the curtain of night?")
I tend to agree with the responses you received from @cd318 and @squeak_king_77 . As examples, the widely used
Equipment Vibration Protectors (EVPs) are offered with either rubber or felt backing on the top or bottom - with no discussion about any change in sonics or performance. Also, Sound Anchor's Conecoaster spike support discs come with a felt-like material on the bottom and I was able to successfully slide my large speakers around on hardwood floors when I used those. Of course, as usual, @millercarbon provided the most reasonable response!
My construction is peer and beam, plywood with 3/4" oak hardwood flooring above it. My speakers sit on out riggers with spikes which sit the Isoclean PowerModel TT-009 Tip Toe Base with a felt pad on the bottom to protect the hardwood floors and make the speakers easy to move.
You can go to a variety of quality audio component rack companies websites and they will show pictures of their racks, with spikes, sitting on a hard material coupler over a hardwood floor. The point is, the spikes are meant to directly interface with the flooring surface. This provides a mechanical ground for the rack and the audio components within it to drain vibration away and into the hard surface on which it is resting. The same function for the equipment rack is also a function for speakers. Felt would interfere with this premise. The coupler, being a hard material and with a center detent for the spike, won't allow the spikes to damage the floor. However, it still is not something that should be dragged across the nice wood floor. Ideally, you would want to locate the speaker to its' best sounding position (carefully, maybe using felt pads only for this purpose) and then remove the felt pads and place the hard couplers under the spikes. Another method is to remove the spikes altogether and replace them with a vibration control footer that does not have a hard spike at all. For instance, the IsoAcoustics GAIA products. They have a nice video tutorial that demonstrates how to install the footers for speakers that reside on hard wood floors. They are well reviewed and nearly everyone who uses them praises them highly. Best to you. Be safe and be healthy.