Re: Boss DS-1 Distortion vs. Boss SD-1 Super Overdrive
To me, the DS-1 has a more artificial, fuzzy distortion, whereas the SD-1 is a more natural overdrive. Stock, the SD-1 has a very muted sound (the "blanket over the speaker" sound) and a pronounced mid-hump. The SD-1 is more dynamic that the DS-1, the DS doesn't really translate your picking dynamics very well.
The asymmetrical clipping circuit makes it a little more nasty than the symmetrical Tube Screamer.
I have modded versions of both pedals on my board right now. A few simple mods really improve the SD-1, taking off the blanket, improving its tonal range. The DS-1 also benefits from mods, I find it unusable stock, but pretty good modded; though it still has that fizzy artificial top end.