Chosen Solution
My MacBook pro and the left speaker is distorted. I’ve tried resetting the NVRAM and SMC still nothing. I’ve Tried plugging in the headphones and its the same issue, its distorted on the left earphone. Tried changing frequency in the Midi Setup still and the issue still persists. The Startup sound is distorted also. At first i Had OS sierra installed when the issue occurred, I tried updating to High Sierra and still nothing. My current OS is Mojave. Update (09/27/2018) Update - now both speakers on the mac make the crackling sound like the volume is maxed out. However, on the headphones it’s only on the left side. I’m really out of ideas now.. Did a hardware check pressing “D” while booting up and it says that there is no issue. i’m at a total lost here
Did you have a liquid spill at one pointer sit the system down on a wet surface? Why I ask is its very odd to have one channel have an issue if the DAC its self was having an issue. I suspect the analog side of the connection has some corrosion which is shorting to ground enough to cause distortion issue. You might also want to try a second system with the same data source or a USB DAC unit to see if the issue is the system or the recording.
It might be a hardware issue too..if you hear music at a loud volume subwoofers sometimes crack, causing distortion. To be on the safe side before getting mad looking for deeper troubles or software issues I’d remove the loudspeaker and give it a thorough check with good light and some magnifying.
