Setup

Head Unit
Alpine CDA-9807

Amps -
JBL px600.2
Alpine mrp-f240

Speakers-

Alpine spx-137r component
Alpine spr-174a 6 3/4 2-way

Sub -
Alpine swr-1241d


Had this system for about a year before getting the mrp-f240 and it works fine. I tuned the mrp to my head unit and it ran flawlessly, no distortion at max volume. However, now my sub sounds awful. Very echo-ey and raspy, little boom and punch like it had beforehand. I have a feeling this is a simple solution, anything I can do?