I have an opportunity to buy a vintage ADA MP1. Is it possible to connect it on the powerhead and use the poweramp only plus the effects?
Using a tube rack preamp with the poweramp of the powerhead only?
Yes, just put a loop in D and deactivate the amp section (but not the cab one). You can do that on a Rig base, so that you can keep using the Kemper normally.
Be aware that a lot of MP1 profiles are available