How can an individual do this? If for example my TEACs are the correct solution (to a problem that there seems to be some doubt actually exists), how can we compare other designs, using lighter casings, different CD clamping, or different feet? Yes, if we know what to measure, there should be measurements from designers but there aren't.
I fear you are sadly mistaken here. There is always bias - knowingly or not - if listening is not controlled (DBT).
If it is louder than it can easily be measured even with the cheapest soundcard. Post results please.
It is simply not practical for me to do any sort of well constructed listening test in my home. It would involve removing and replacing shelves (7) and feet (15) as well as connecting and disconnecting cabling (which could effect things). I only have REW and I wouldn't rely on that for proof of 1dB changes. And 1dB was the amount I turned down the digital volume control, so satisfying myself at least that the music seemed louder with the isolation gear in place.
I'm not convinced there was bias. Of course I could be deluded. They were tests to see if this equipment would be beneficial or not. It's expensive so I didn't particularly want to buy it. I was listening for small changes in the higher frequencies - percussion. I thought I detected small amounts with shelves and feet under the amp and CD Transport, and shelves under the speakers, but no change from the DAC and equaliser. After a while I got fed up and decided just to listen to the music. That's when I noticed the subtle changes, including being slightly louder.
It would be easy to argue all sorts of explanations other then isolation for the changes apart from that there weren't any - raising the speaker height (shelves are 15mm thick), movement of speakers (I place them in an exact spot and toe in), maybe others. It doesn't matter to me now!
I would have thought the best place to measure the impact if any of isolation equipment is the output signal from the gear concerned - so for an amp, at its speaker terminal. What exactly is to be measured I don't know.