Cloud Microphones Cloudlifter CL-1 Mic Activator

I use this together with my SM7B going into a Pre73 and get great results. It is a very simple and robust design, although it weights more than I thought (concidering its small size) so it requires some flat place to lay it on or it could be mounted on a stand.

All in all a great alternative to give more clean juice to the signal of a low output mic.