Unbalanced and distorted audio out from jack. what to replace?

I've got unbalanced audio (Either calls or multimedia) out from jack connector.

The right channel is very good. Instead the left one has a very low volume/power.

I've checked the audio balance setup in "accessibility" options from the Settings app and it's on the center.

I've tried out other pair of earphones/headphones which are perfectly working on other iphones.

I've noticed that playing a loud track lead left channel to "unlock" and so for few minutes i got balanced audio!

after theese everythings come as explained back.

Forcing the balancing through the menu doesn't fix the problem because i eventually got a pair volume on both channels but good quality on the right and poor quality on the left.

I'm used to listen music through dockstation and car-audio system through dedicated usb cable.

on these scenarios the audio is perfectly ok in both channels.

My ask is : replacing just the jack connector (with maybe the flex cables etc) will solve the problem? i read out that the problem would be caused by Audio IC.. is this my case? thanks for replying

edit/update: i've just replaced the jack assembly with new one and i've just got louder but still unbalanced/distorted sound through out the earphones, so i assume the problem is elsewhere.. any suggest?