I just installed 2 12in subs and when I try to adjust or turn on my HPF on my HU it kills all the bass coming from my subs. What's wrong? Hu is a pioneer fh-x700bt. Thanks
All the above. If the headunit has SUB RCA outputs it needs to be on those. No HPF needed ever on subs, unless it's a subsonic that could help your subs from injury.