I use the Nimbus couplers and spacers from HRS under my ARC CD7 and think they do a great job in reducing airborne and floor based vibrations. I found that my bass tightened up somewhat, and the resolution as well as image focus tightened up a bit. If you have an HRS dealer locally I would ask for some loaners to test out.
http://www.avisolation.com/nimbus.html
http://www.avisolation.com/nimbus.html