Vibration Isolation

@lak   I believe that either "Goo Gone" or "Goof Off" should, with some elbow grease help you to get rid of the black marks.  

@hifiman5, thank you for the information. I'll give it a try :-)

I recently contacted Diversitech (email) and asked about the Durometer spec on the 2x2" EVA (blue center) pads. Hoping for a reply. FWIW - one of our senior members had recently opined that these will do nothing for audio as they are too hard. I am not voicing an opinion in that regard. I have both blue center EVA pads as well as the cork center pads. It would be helpful to know the Durometer value and relevant Shore scale as this will allow comparison to some products from Herbie’s Audio Lab (with which some of us are more familiar). If interested see also the chart at the link below.

https://www.smooth-on.com/page/durometer-shore-hardness-scale/

In my experience too much rubber of any sort under too many pieces of gear in one system can mess with timing (PRaT), darken the sound up too much and/or slow or loosen the bass too much. Took me a few years to work the rubber/cork/rubber out of my system and into Herbie’s Tenderfoots, then out of those and into an even mix of Daedalus Isolation Devices ( ball bearings incorporated with dissimilar materials) and Isoacoustics ISOpads (yes, some rubber implemented but mainly spring based), both in the right places.
I realize this may be in a completely different price bracket as the thread subject but just saying to be careful using too much thick rubber under your components. In my experience it can give a false sense of warmth and body that is actually screwing with the presentation of your music. In general possibly robbing the music of some of its life and breath. —Revealing/transparency level of your system will dictate this outcome...or not

@ianrodger, thanks for that. I think it's time I looked outside just the UK sites.

I have found isolation works well under loudspeakers, especially those that might suffer from a boomy bass. My Tannoys took a step or two towards neutrality when provided with a measure of isolation. They have a lovely full warm mid bass, but previously it could be too much of a good thing with certain recordings.

Ultimately when it comes to isolation I find myself agreeing with geoffkait (shock horror!) in that springs are probably best. However because of practicality and cost these anti vibration pads are a great alternative.

It's also reassuring to see certain speaker manufacturers such as JBL now starting to offer isolating feet and or instead of the ubiquitous spikes.

Furthermore, isolation blocks under monitoring/mixing speakers are also becoming more common in pro use.