2.1 Audio system low bass sound
I recently got an apparently faulty logitech s220 2.1 speaker system. The speakers sound fine but the sound of the bass is very low almost inaudible. The system has two volume controls. One is the main and one for the bass only.
Both seem to be working properly as on max volume there is sound coming out from the bass but if I turn either of them down the sound dissipates. The bass speaker itself works. I tested it on another system and also with a multimeter.
On the back of the PCB where the IC is soldered I saw light brown burning signs so I thought the IC is out and replaced it with similar one (CD6282CS) as I couldn't get the exact same model (D6282). The problem is the after replacing the IC the exact same problem still there. The bass is still low. Images of PCB: https://imgur.com/a/atG4csf
So my question would be how should I proceed from now? Is there a way to figure out quickly and easily what could be wrong? I would be happy even with high probability guessing too if that saves me from pulling out all the bits and bobs and testing them one by one.