[crowdog]

I've been using the dbx-576,which is 1 channel of tube (12xa7) preamp & 1 channel tube comp.
You can feed the preamp directly to the comp or not and can use both on different sources at the same time - also has sidechain capability & an option (more bucks) of digital output - I've used it on elec bass, acoustic guitar, vocals,percussion - hell everything I've recorded with a mic - it's made a big diff!! Plus it has some classic dbx compressor settings (over-easy). I got it from sweetwater for $750. They also make the 586 which is two channels of the same preamp for the same $$.

Good luck!!

crow