SM 57's sound very much like SM57's in my experience.
The fact that different input impedances change the sound of microphones is a given.
thats why you need a range of different mic pre amps to broaden your palette,
its also why you should have loads of different microphones.
By all means remove the transformer or even get an upgrade transformer
add series resistors if you like but for certain you wont make an SM57
sound like an LDC or a ribbon mic.
So if you want a dynamic mic that has a smoother better controlled top end
buy a Sennheiser MD 441 and leave the bright switch in the off position.
But remember the SM57 is still a classic sound so always have a few stock ones hanging about for where they suit best.
