Between Snes9x 1.51 and 1.52 is when there was a major sound core overhaul, or when Blaarg's super-accurate SPC700 emulator core was integrated into the program code. Many games that sounded horrible on Snes9x 1.51 have been corrected in 1.52 and on, like Super Mario World (the spin jump sounds, entering/exiting a warp pipe, mushroom shrink/grow) now all sound like the real thing. Does the golden goddess statue sound really bother you that much to the point of rolling back emulator versions?
You're definitely entitled to your opinion, don't get me wrong, but is Seiken Densetsu the only ROM affected? Do other games sound weird as well? I can certainly run comparison tests between games like Chrono Trigger/Final Fantasy V on Snes9x and a real console (since I paid 500 Yen for the used cartridges and 1000 Yen for the console). I was and still am very nit picky about how sounds are emulated, especially the Square cursor sounds, or the Lightning 2 sound in Chrono Trigger (Zsnes/Snes9x 1.51 made my ears bleed, but 1.52 and on get it 100% correct).
One last question, have you tried Bsnes 0.82 (which, according to Byuu, is the fastest version)? It supposedly emulates the sound better than Snes9x, but I can't tell the difference. In fact, many test Bsnes against a real Snes.
Are other ROMs affected? Again, I personally don't think it's an issue per se, but designed to have the buzzing/humming sound. In fact, it sounds almost like the Mega Drain sound from Super Mario RPG that enemies use on you. That I know for a fact is how it's supposed to sound.
I'm not trying to convince you to use 1.53 against your will, but if it looks like that....sorry. You're entitled to your preferences, it's just that other games (besides SD3) sound wonderful compared to 1.51.
If anything, Bsnes should be 100% accurate with sound. (Info about Blaarg's DSP/SPC core, bottom of the page - http://slack.net/~ant/libs/audio.html#snes_spc
Here is a video from Bsnes, the most accurate Snes emulator out there http://www.youtube.com/watch?v=nTNS86BqIaU