Hey guys, i have an unusual problem. My left front speaker plays much softer than the other three. When isolating the sound output, the other speakers play as loud on setting 7 as the lt. front plays on setting 15. I've switched it with the pass. side speaker and the result is the same, so the speaker is good. The immediate wiring seems fine with no visible splices. The head unit is an alpine 9856....both the speakers and HU are only ~2-3 years old and barely used as this isn't my DD. Any ideas here? TIA