In addition to (NOT instead of) isolation, you MAY (or may not) want to try the Dakiom Feedback Stabilizers. For me, an EXCELLENT tweak, at least with my previous speakers (Paradigm Studio 100 V3's). With the Paradigms, these gave BOTH more detail AND more smoothness on the high end, PLUS the bass was noticably deeper and tighter.
{{{{{ NOTE: I haven't had the time to A/B the Intuitive Design Summits with and without them, so I've left them in place since the get-go with the Summits, and the system sounds astonishingly wonderful beyond all possible belief (although that's mostly due to the Summits, the Dodson, and the Odyssey Extreme monoblock amps and preamps).}}}}}
Another great thing I found: The Dodson 217 Mark II D DAC. Phenomenal improvement. Even more so than the Dakioms, I'm pretty sure, but also WAAAYYY more money (but worth every penny). The 218 is said to be even better.
Don't give up. I had the same problem with my old system and it's.....GONE!
Bill