Some folks said a while back that Splawns have weird mids. It turned into a running joke. I've always said, the QR sounds like a very angry 2203. That's my story and I'm sticking to it. LOL!
To me, they don't really sound like Greenbacks. They're tight and powerful sounding. Greenbacks are looser and more vintagey. I don't really like them with my other amps, but with the QR , they're the shit.