My Mac Air won't let my headphones listen to music

Hey I have a problem the only thing is that i tried what you said and the incresing volume thing didnt work either but for some reason when i try to do your solution i go to sound prefences (and keep in mind my headphones are connected ) (in the output) like you said the (Digital out) just says (optical digital out- port) and on settings for selected device its says (the selected device has no output controls) and at last the (Use audio port for) says (Digital Out) do you have any advice at all.

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