The Basswitch has switchable A and B inputs/channels, one routed via the eq the other isn’t so you could have your active MM bass into that input and use the jazz into the preamp input which means you can match output volume, have the DI as well as the fx loops etc. One was up for sale on here recently but I think it shifted pretty quickly. It’s so much more than a preamp it’s a really useful tool designed for the working bassist who uses a couple of basses (I think the idea was for folks using both passive and active basses), who needed some eq and fx loops (there is both series and parallel options).