Oh, so hey, I've been derailing this thread like crazy, but now I have something to bring the topic back to the gsu beta--and I owe it all to my earlier thought about an MSU-1 version of Street Fighter Alpha 2 (though I still think this idea is swiggety-sweet *wink*).
I have a Rev. F SD2SNES, and with the most recent ikari firmware a +12dB audio boost is about right for most normalized MSU-1 games, but when I swap SD cards to the one that has my GSU beta firmware (v08, but of course), that is WAY TOO LOUD, and I have to turn the boost off. So I think this firmware may have broken the audio boost option. Can anybody with both firmwares readily available see if you can replicate this problem with MSU-1 stuff?
I suppose it's preferable to test this on an older SD2SNES like mine, though I wonder if the problem might not be even worse on rev. H.