Good points - it's likely that I won't be opening these up anytime soon. Most of the synths in question take 12V @ <800mA @ 12V (so ~10W) and usually come with

Good points - it's likely that I won't be opening these up anytime soon. Most of the synths in question take 12V @ <800mA @ 12V (so ~10W) and usually come with a 12V 1A supply. Or they take 9V (current ranges). And there are a few that take USB power already. I'd imagine everything being either on or off and not having to hit the first problem too often. The second problem is something I'd definitely avoid. I think I only have one or two odd values (5.7V etc.) Definitely something that's more of a pipedream - I hope someday synth manufacturers will just settle on USB-C as the common power standard instead of having something different for each device.