Since you have a dedicated preamp like the Radial PZ-PRE that is optimized for orchestral instruments, it’s best to connect your violin to that first. This way, you can make use of the onboard EQ, notch filter, and effects loop.
Deciding where to put the H9 Max depends on whether or not you wish to run stereo audio. Do you have a stereo playback system?
Option 1 – If mono is okay, you may put the H9 Max in the effects loop of your PZ-PRE using Input 1 and Output 1 of the H9. Then you can connect the output of the PZ-PRE to your mixer or speaker.
Option 2 – If you want stereo effects, then I would connect the Post EQ output of the PZ-PRE to Input 1 of the H9 Max and the outputs of the H9 to stereo inputs of your mixer; this will require either using two tracks on your mixer hard panned left & right or using a dedicated stereo input, if it has one.
Option 3 – Connect the H9 Max to the effects loop of your mixer, if it has one. This way you could route signal from any instrument or Mic connected to the mixer and send it to the H9 Max using the effects send; in this case it would be best to run the H9 in kill-dry mode.
Let me know if you need any clarification.