A question about power amplifiers (and/or SMPS design)

I like the small supply idea. I'm not sure what the upper limit for the main amplifier is, so before I try that, I'm gonna crank it up on a variac to make sure it can take the extra oomph. Do you think it would be possible to build a 0-30v negative supply and have it be a subtractive thing?

I'll be sure to share lots of pics and video (and more detailed info!) when I'm done. I'd love to see this become a kit that most hobbyists could build as long as they have a scope and a variac (and maybe an isolation xformer).

Yes you can add and subtract uing a seperate supply, it must however be isolated.