@lewm You intrigue me to dig into the decoupler/isolator subject. Here are articles, some support it and some don't. Please take it with a grain of salt. I went through several bookshelfs, starting from my 1st (NHT SuperOne 2.1) 25 years ago, Tannoy Mercury F1, Sony SSCS 5 and currently this Elac. I placed the IsoNode isolator underneath without a second thought back then because, just like many others, I heard noticeable difference in bass, tighter and cleaner. The effect on the subwoofer is even more pronounced. I think very few audiophiles will debate the benefit of using damping isolators under the subwoofer. I compared the $50 SVS Soundpath isolators with $3.5 a set of four damping isolators you could get from Walmart. Very subtle different. As a band bass player a band in college, I could testify that is not a placebo effect.
I place the similar IsoNode isolators under the gears including CD/SACD player to reduce the vibration. With that, the gap under the player has increased to 1+ inch to help dissicipate the heat from Parasound to answer @slaw, although I do agree a audio grade rack placing them individually will be more ideal. BTW, the heat from Parasound PA is much less than the Cambridge IA I had for being a similar class A/B design.