I recently bought Sennheiser Momentum 2.0 bluetooth headphones and I use them mainly with my imac. After a bit of fiddling I figured out to force aptx via the bluetooth explorer and disable the handsfree profile as well, as countless people are recommending.
At this point I'm pretty happy except for one minor annoyance: I can't connect the headphones without OS X insisting on dropping the sound quality as if it were receiving a call and then deciding it is not a call after all and switching back to normal quality. I'm not sure if this is specific to OSX or the momentum 2.0, or both.
Symptoms: I turn the headphones on. Almost immediately it announces "connected", as it should. If any music is playing at this point it first plays at good quality but almost immediately it changes to very low quality. After a few seconds the head phone announces "call ended". From then on everything is fine.
I've been searching for a resolution to this but I haven't been able to find anything that even confirms this is a known issue. So, is there a way to skip the whole connected ... call ended ritual? I'm not actually interested in answering any calls with this thing.