yes, the power amps look like the transformers flying leads are hard wired to the PEM (power entry module), but the smaller HP and preamp products have PCB mounted transformers, and possibly configuration jumpers. helps to have a variac to bring the mains up slowly when first re-powering (just in case).
all this moot if warranty gets voided by changing the voltage setting.
I would be incredibly surprised if taking it apart and changing the internals didn't void the warranty. They also have a warning on the back stating "no user serviceable parts" which pretty much confirms it.