In the form I described, although Heath Robinson without a doubt, if should work very well
Obvs although the amp needs to be 75W+ @ 8R in order to do the Volts it would only be delivering say 3W and should run pretty cool....
If you have say a <0.01% THD amp and <0.01% THD sine wave from the PC, its frequency derived from the PC's quartz clock, that's a pretty low distortion and accurate TT PSU
With a little ingenuity I guess you could use stereo channels of the power amp to drive each phase of the motor... and with the right sine generator app be able to generate the sine waves with control of relative phase and level to optimise any motor
I'll bet its been done. it's not rocket science. A sound card, a pot for fine control of level, a £70-ish Chinese Behringer or similar 150WPC shit PA amp and you have one hell of a potential 24V AC TT PSU with every parameter adjustable at your PC screen
Hmm.. some surplus 100V line transformers like almost every one must have laying around
D
) could step it up so it works with "240V" motors