The reamp (PRORMP) ensures that the impedance going into the input of the bass head is the same impedance of a guitar, and the level going in is once again the same as when you used the guitar. To hear the difference, try an a/b switch from two outputs from the LP16 with the same mono wave on both tracks saved at the same output level on the mixer, and run an unbalanced cable from the first channel to A, and the second through the TRS to XLR male adaptor into the female input of the RMP (or equivalent) then out the 1/4″ output with an unbalanced (guitar cord) into the B input of the A/B switch, then out of the A/B switch into the input of the bass amp.
Then playback the LP-16 and switch between the A/B sources listening to the difference. To my ear, I hear a better level and signal through the RMP-side. I hope this helps.