I play my basses--all of them including my two Kilotons--directly through our sound system and through an Ampeg SCR-DI. It's very simple, with volume, 3-band EQ, treble boost button, bass boost button, and distortion module (which I personally never use). It has a 1/4" thru, a 1/4" out, and an XLR out. My basses have MFD pickups, Alnico pickups, and ceramic pickups. Some are active, some are passive, including my SB-2 which is wired to a single volume pot that's also a push/pull for series/parallel and my NS Design WAV4, a now-passive bass which has a Lace Alumibar pickup and also has no tone control. Once I got the sound set up for one of my basses, it's been satisfactory for all of them. I've never had to touch any of the EQs, neither on my Ampeg SCR-DI nor, according to our sound man, on the sound system (which is pretty much set up flat on the bass channel). So maybe try one of these preamps or another one inline with your amps, even if you're using someone else's for a gig. I have no affiliation with any aforementioned company.