Rane DC24. Two-channel line-level dual-band dynamic processor.

Rane DC24. Two-channel line-level dual-band dynamic processor. Comes with original power supply.
I have four to sell, but this price is just for one unit.

This one has long been known as a favorite among bassists. It is a two-channel line-level rack unit with an excellent crossover built in, so it can be set up as a dual-band processor. This allows it to compress the highs or the lows independently, only affecting the frequency range that actually needs it. This prevents "drop outs" of your signal when a big bass peak hits, by allowing the highs through uncompressed. Because of this it is very good for a consistently articulate sound across the entire fretboard, as well as being good for heavy hitters who need to keep a lid on it while still sounding somewhat natural.
 
There is barely any noise at all, and no rolloff of the highs or lows, although the low end is not quite as "big sounding" relative to the highs and mids, compared to some other comps (this is common with multi-band compression). The crossover point has no artifacts that I can hear, although different settings will affect the way the lows and highs are heard, like using an EQ. The overall tone is very transparent. The limiter function is pretty decent, and not especially prone to "pops" or other artifacts.