Here is the manual - Peavey PV BT 6 - https://peavey.com/ItemFiles/Manual/118741_30948.pdf
The main output left and right of the kemper 1/4" with balanced cables are going into the mixer on channel 3 and 4.
The main out of the mixer is going to the Adam A5x monitors.
I do have a similar setup, but using a Yamaha mixer and speakers. No issues at all. As Wheresthedug mentioned above, it sounds like the delay is coming from the mixer on board FX. Check that channel 3/4 EFX level is set to zero. Use the mute EFX to be sure no FX is added to the mix. If you still hear delay, please send a picture of your mixer settings and connections