I have the SD-1 and like it quite a bit as a level/gain boost into my amp. The thing about the SD-1, is that it has kind of a treble boost effect. It tends to to make an amp quite a bit brighter than it ordinarily is. I use it with a 120 watt tube amp and a 4x12 cab, so I have low end to spare. The SD-1 gives it a nice crisp 'bite' - but if you have an amp that is already bright, you might not like the effect.