Max,
This is something I'm looking into right now, so I'm no expert whatsoever. Yet I've been doing a fair amount of reading.
An isolation transformer is not the same as a regular transformer, being it a stepdown or up. The difference is in the way the primary and secondary are wound. Maybe try searching online for a much better explanation. An isolation transformer is aimed at reducing the noise that is carrierd on top of the AC sinewave from getting onto the secondary, so you get an AC sinewave on the secondary with less noise. A grounded RFI shield on the primary is also used. So that's the benefit of isolation.
Balanced power refers to a different approach to obtaining 110V difference in potential from two connectors: your regular home line has 0V on the neutral and 110V on the hot. When balanced, you get +55V on one connector (hot?) and -55V on the other (neutral?) so you end up with 110V anyway. Now if you have an isolation transformer that receives 110V & 0V on the primary and delivers +55V & -55V on the secondary, you get both isolation and balanced. Balanced power has the added benefit of further reducing the noise superimposed on the AC as seen at the component (power amp, pre, etc) as the noise incoming to the transformer gets symetrically reproduced on + & - on the secondary and by the time that mirrored noise gets to the component each side of the + & - cancels each other out.
Boy, I sound like if I knew what I'm talking about. I don't! So anybody who really knows this and wants to jump in, please do.
nevertheless I've discussed with several users and they report very good results. I'm gearing up to try it.
I hope it helps.