My system uses isolation transformer based filter arrays (Clear Image T4) and there is a definite improvement. I can see your point, Detlof and I use serious vibration control measures on my transformers to enhance clarity and resolution. This has been one of the great lessons I have learned: how vibration affects electricity. Nonetheless, the overall result is better than before.
By the way, I'm still waiting for the pictures...
If one wants to try isolation transformers, the best place to start is eBay. ONEAC isolation transformers are pretty much musically benign and can be gotten cheaply through eBay for $10-$40 used.
Isolation transformers benefit greatly from vibration control measures. Detlof is correct.