Mine was at about 19V too. I did try hooking the PSU to a Variac and testing it at 18V, 17V, and 16V with no luck.
Ruled out everything that's not the amp though by plugging my CPS2 setup into my Behringer amp... The problem definitely lies in the Q-Sound amp somewhere. 2 NOS amps and neither work T_T.
On the hunt for: Dinoking, Mushiking, Love & Berry, Egret 29, Grand Am Q25, Capcom New Concept 2, and Naomi guncabs.