For some reason pd doesn't cooperate with my Bose Soundlink bluetooth headphones on my Macbook (2015, running next-to-latest OS, most-recent pd and pd_iork builds (tried on both)). It only does audio from the right inlet of the dac~, which it interprets as mono--the left inlet doesn't work at all and there is no stereo. Other than pd the headphones are fine and stereo and everything. And I made sure the audio settings had it listed as 2-channel.
I tried the same thing on my Windows computer and found that Windows has an option where those headphones can be interpreted as either headsets (1-channel, apparently what pd says) or headphones (stereo)--by default I was getting the same 1-channel response as on the Mac, but I was at least able to change it in the Windows preferences, an option that seems not to exist on Mac.
How can I tell pd on the Mac that they are stereo headphones, so I can work with both channels? (Or, and I realize this is a Mac question, not pd, how can I slap some sense into the Mac?)