many years ago i fitted a car power amp 25w x2 into my PSU. it worked fantastic. all i had to do was connect the two phone leads into the back of the A500. the PSU fan kept the amp cool at high volume. so one power supply powered eveything except the monitor.
today i still use a car power amp on my PSU 25w x2,but the power amp is now external,so one power supply is still powers everything.
the final part of my project is to fit 25w x2 amp into a A1200 desktop.