Discharges SMC and NV RAM did not help! Now I use a Bluetooth column HK Go+Play Mini.But Bluetooth headphones yet, but sometimes you want not to disturb the others and the presence of 3.5 mm were allowed to use epplovskoy headset ( the Laptop is not exactly bathed and worked mostly from home as stats.comp. Do itself could break 3.5? The system was not perestanavlivat , I am afraid will not help - since the first day immediately grabbed a bootable flash drive El Capitan( although it is Mojave). Wanted to roll , but when I immersed myself into Recovery with the usb, put on the headphones and heard the same background in headphones(( I Think to reinstall the system?