The common issue with Bluetooth Audio and mac OS I recently purchased an Anker Bluetooth Headset, and i had the common issue that it sounds like garbage when i pair it on my MacBook but awesome using my iPhone

The issue is fixed by turning "Input" to "Internal Mic" in

Settings > Sounds > Input

But the thing is.. i have to do it EVERYTIME i connect my earphones! If i need to charge them, the second time i turn them on, i have to do the same process again, is there a way to make this the default behavior?? 

BTW, i'm using High Sierra
create an aggregate device via audio midi setup and do not include the your headset input channel in there, then make that device to be default.

that's an example setup, as long as you do not include your headphones input and use the build-in microphone, it should not trigger the SCO codec upon bluetooth initialisation. that generally means if you want to listen to music and talk it will use the laptop microphone, not the headset one.

hope that helps.