Bluetooth?! Really?!
Very recent purchase, former Sennheiser customer, I chose these headphones with my eyes closed...
Ok the first day, then very quickly of big problems of connection appeared and very many attempts were systematically necessary to manage to connect it that it is about a PC or the smartphone.
First of all, a reset seemed to work, then again, after switching off the headphones, it was impossible to connect them, and the headphones seemed to switch off in barely a second... on your PC screen, you just had time to see 'connected' at the same time as you heard a confirmation sound from the headphones, but there was no sound after that: the headphones seemed to switch off instantly without you hearing the usual 'power off'.
In wired mode, on the other hand, no worries: the sound lives up to the brand's reputation and the finish/comfort is good.
After scouring a few forums, it seems that this problem is systematic, and I think that one user's theory may be right: it could be a problematic update that causes the chip to require the wrong voltage...
The only solution he could find to this problem was to have his headphones changed and charge them only via USB on his computer, so as to have only a low voltage when charging, because yes, no wall socket is supplied with the headphones, only a usbA-usbC cable...
Some people talk about leaving the headphones on until they've discharged enough for the connection to be possible again... but for that to happen, they'd have to stay on...
So I'm going to have these headphones changed, hoping that Sennheiser will quickly react to this problem, which is as major as it is unworthy of their reputation and the usual quality of their products... unless I don't have the courage/patience to have to plug them in indefinitely via the computer if they take too long to fix it, and if, of course, this "solution" found on the forum is effective...
