I've read a few older posts about headsets and the TRRS headphone/mic input here, here, here, here and the consensus seems to be that the Macbook is expecting "line-level" input (either that or you have the mysterious occasional answer of "mine works!").
My question is more clearly related to this answer: which is, if these Macbook Pros only accept a powered/line-level input, then how do they recognize the iPhone earbuds/microphone? I have not seen this addressed anywhere else.
My Turtle Beach XO Four Stealth is not powered, its only hookup is a TRRS jack. When I plug it in the Input doesn't switch from internal to external as it does for my Apple earbuds/mic.
Any explanations for the difference in behavior? I assume this may just be dependent on the hardware of the headset, but what would this difference be.