Anyone cure hum with isolation transformers?

Bondmanp,
In my experience an isolation transformer will not correct or prevent a ground loop hum problem.
My isolation transformers (Xentech Extreme 5 KVA and Equi=Tech 2Q) do make my entire systems sound better by lowering the floor noise which in return gave me more transparency, depth, air, and detail with improved bass, mids and treble.

I'm not sure if this is the type of isolation transformer you're refering to, but I used on of these: Ground Isolation Transformer to eliminate a ground loop caused by my TV cable connection to my HT system. It worked great with no apparent adverse sonic affect.

I've been able to reduce noise and cut hum using Jensen transformer isolation devices. I've observed no adverse insertion effects from these. Here's a link:

http://www.jensentransformers.com/iso_aud.html

Check out their CI-1RR and CI-2RR products (about half way down the web page).

Thanks, all. Due April's flood, I am just now about to reassemble my system. I will work backwards from the amp in order to locate the source of the hum, then try the appropriate device. I'll report back.

Well, once everything was connected, the hum was gone! Go figure. However, the ac power is still a bit noisy, and there is a much lower level buzz, audible only quite near the speakers. I will address power filtering, but for now, it's a back-burner issue.