Weird cutout/static on speakers

[sparten576]

Hello,
I've had my car system in for some time now and have always had a weird issue where one speaker (or multiple) will cutout randomly and have this static sound to them, see video

 

 

(sorry the song was on the radio and it produced the sound)

 

 

start at 35 seconds

Things I've done to try to fix the issue:
replace the 4 channel amp (twice)
replace all the speakers (twice) (These ones i'm positive were damaged from the amps since both amps had bad channels and popping issues.

 

Do you guys have any ideas what is going on?

(4 channel amp, aftermarket head unit)

 

Other things i've tried:

I've already ruled out the radio by using my phone as a source.

Add thicker grounding cables from negative terminal to strut tower.

 

Other observations:

I spent a good chunk of time moving things, disconnecting speakers, setting different crossovers, gains, and measuring a lot of things.
I think i've come down to the in line crossover for my speaker taking a dump.
I've discovered a repeatable phenomena where the speaker in question will play very quietly compared to the other speakers, unless i turn the volume up a little at a time. Lets say at 5/10 volume all speakers but the one in question is at 70db
when i turn the volume up to 6/10 it will start playing on and off at 70db but heavily staticy and crackly like the above video. If i turn it back down to 5 it gets very quiet again, if i go back to 6 it starts playing again on and off but with the sound issues. If i go to like 8/10 it will always be on but be very back sounding

This is repeatable with my phone as the source and is always the same speaker no matter what terminal of the 4 channel amp i use.

 

These are the speakers that I'm using https://www.crutchfield.com/S-moE7DQgsMKs/p_113XP6903C/Kenwood-Excelon-KFC-XP6903C.html

 

Any ideas? It almost seems like the crossovers are just hard cutting off the sound.

[Dafaseles]

Well, no one replied to you. I'm not an expert but I don't want to leave you hanging either. 

First thing I would do is check all the rca connections and make sure they're tight and not pinched or crimped. Then check the speaker wire itself and see if there's a bare wire grounding to some metal or something. 

See if you can manually replicate the problem on purpose. That might lead you to the problem as well