If the bicycle inner tubes are not working, try using one of those inflatable hemorrhoid cushions that can be bought at almost any pharmacy including Target, Walmart, CVS, etc. They are a lot wider than inner tubes and made to hold a lot of weight, i.e. your ass. I put water in mine because water is more dampaning than air. Works for me.
Sand bags under a cdp - didn't work well
Last night I started the process of vibration control with the use of sand bags (3) under my Arcam cdp. What I found was that while everything became more focused/detailed it also became more sharp/harsh/forward/aggressive. I didn't know what to expect but it certaintly wasn't this. Van Morrison's voice on trk #5 on Sailing to Philadelphia was abnormally aggressive and in the end I preferred the sound without the bags. Any thoughts as to why things became too sharp & aggressive????