No, not at all. Had you not introduced me to these isolated dc dc converters I wouldn't have discovered them myself in all likelihood. Finding a 25V version was pretty trivial once I followed your link so you gave me a shortcut.
My control logic is obviously coming from an Arduino which is 0-5V but the amp output depends on my supply voltage which I need to be about 25V. The Concern is not with the top end... I can rectify mains voltage for as much + supply as I want but I can't go any lower than 0 with a single supply and that happens to also be the bottom limit of the Arduino outputs so the amplifier will never actually reach 0V, which means I have no way of charging say a single ni-cd at 1.2V. Having the - supply merely gets me sufficiently far away from 0V to allow the amplifier to work all the way down to 0V.
So it looks like these isolated converters may be the most compact way to do what I want to do if I plan to stick with linear amps. A small xformer could work too but after making the high frequency switching circuit I may end up adding just as much bulk to the entire assembly. There seems to be no other easy way of doing what I want to do unless there is a single IC solution out there that converts mains to high frequency that I can then hook up to a small xformer, thus saving me the work of making one myself out of discrete components on a proto board.