I've got two macbooks, one late 2013 model and another newer one that I use for work. I've got a pair of B&W PX7 headphones which I use on my work macbook and phone without any issues.
However, when connecting them to the older macbook, the microphone is extremely low (might not pick up sound at all. Testing in sound preferences gives no indication, but on zoom I will get a weak (one red bar) sound level at times).
I've checked the MIDI settings as well and can't see anything weird. The built-in microphone works without issue. Any ideas?