I suggest running your compressor post eq.
Run through your eq, then your compressor, then the speaker. So if you were using an eq. You'd wire the "send" from the eq to the "in" of the compressor. Then you'd wire the "out" from your compressor to the "return" of your eq. This way if you want to defeat the compressor, you can still use your eq. This is the most straightforward way to add an effects processor to your eq rig (my effects rig just happens to have a compressor).
However they do make compressors in the form of active direct boxes. In this case, I still suggest running through your eq and then into the direct box. Or, you could go from your bass directly into the direct box, then into the p.a.
