Just to add another voice to the chorus, because sometimes this matters 
I'm on v12, I've been working with different power supplies all week hoping there was one that would reduce the noise enough for me to use the OWL onstage this weekend, because I'd kind of (eh, stupidly) built an arrangement around it. I bought an Ojai (before reading this thread, which amazingly works sometimes) as a last resort, and it's absolutely no different, this +15-20db F# whine. So today I'm going to buy some cheap shimmer verb to use instead, point being that it remains a bummer it's not stage-ready.
