This reminds me of the story about the guy who's down on his hands and knees in the street one night, looking for a key that he's dropped. A passer-by wants to help, and asks him, "Did you drop it close to this streetlamp right here?" The man says that, no, actually it was about half a block away--but he's looking beneath the streetlamp because the light there is better.
Most of the sound quality of any condenser microphone is determined by its capsule(s). And the main problem with the Superlux (I actually happen to own one, which I bought a couple of years ago out of curiosity) is its mediocre capsules. The average hobbyist can't do anything to improve those--even most professionals can't--so instead, people look for modifications to the circuitry. And who knows--maybe the amplifier could be made a few dB quieter with more careful selection of some key parts.
But you can't expect that to make the microphone actually, you know, sound good.