Behringer Multicom Pro XL
Behringer Multicom Pro XL
Four channel studio compressor 
I needed a unit to compress and raise the dynamics of both my AN200 and DX200 desktop synths. By no means was this expensive and as it turned out, it proved to be perfect in its designated role. The unit has a four channel capability. Channels can be linked into stereo groups which is ideal to avoid unbalanced signal attenuance.
I would not recommend using this unit on a complex mix or mastering compressor; as a single instrument expander/compressor it really is fine.
Read more about the Multicom Pro XL compressor at the Behringer website