Even if the PSU voltages come out right when you test them with the meter, it's impossible to tell for sure unless you test it under load. The meter also doesn't test the quality of the power. Often, dirty (fluctuating voltage) power will cause problems with audio, mostly pops and static.

If the cord coming off the PS is red and black, that should be power, same as any other red and black cable. If it were me, I'd just do some rewiring, but I guess I can't recommend that because you could do damage to your hardware if it's done wrong.