Hiss sound on left output in lo freq

Hello people

I am having a trouble here.
I recorded a bunch of drums...
and whenever I play back the kick's from my MPC
I get a hiss from my left output

Note: It is left output and not left speaker. Speakers cables connections checked
I also tried to whipe-clean the inner of the left output but still the same.

Anyone knows what could it be?

I am going to do a small surgery
but would like to ask here first.

Is it the output thingy? Maybe inner cable connection?
Please assist me

Regards