From factory speaker signal -> LCi2 line converter -> MTX Thunder500.1 500 watt amp -> two 12” drivers in mid-ported box. 2023 Hyundai Elantra factory head. I just hear the very slightest delay from the sound of the kick in the factory speakers and the punch of the subs and it’s driving me crazy! Sometimes I can ignore it but others it seems to distract me from enjoying the music. Sometimes it feels too separated from the music. I put on “kick drum metronome” on YouTube and confirmed that the subs are just very slightly behind by milliseconds. I tried changing the polarity of the drivers with the speaker wire at the box and it did not seem to help. The amp does not have a 180 switch or knob. It does have gain, LPF, subsonic knobs and bass boost switch. I felt like I heard the delay before I switched from a dumb converter to an active converter too.
Is there anything I can troubleshoot? Could the factory unit itself be delaying sound to the back?