Questions about Sony WH-1000XM6

There is no predetermined breaking point per se. You can read Sony's warranty conditions here: https://services.sony.ch/support/files/warranty/pdf/warranty_de_ch.pdf

The current model series continues to support the Bluetooth profiles for audio (A2DP) and calls (HFP/HSP) as separate device profiles. This means that during a call on PC or Playstation, you will still only hear the voice-optimised call quality as soon as the headset is connected as a headset (hands-free). The full audio quality is not available during a call, as the headset is then running in HFP/HSP mode. This behaviour has remained unchanged with the WH-1000XM6. The official product data and manufacturer's specifications do not confirm any change in this behaviour compared to the previous model.

The connection via Bluetooth with Windows 11 is stable. Even with MS Teams calls, the voice quality is clear and without any noticeable delay.

I have a Sony WH-1000XM5 and it's practically useless for making calls in an environment with background noise, I keep getting complaints that the call is very tiring due to the background noise. On the other hand, with all my Jabras (Evolve 65&75, Evolve2 65&75) I get consistently positive feedback regarding the voice quality for the other side. I have not tried XM6 vs 85, but I suspect that there is no significant difference compared to the older models. Conclusion: for telephony, Jabra

Yes, when you connect the 3.5mm cable, Bluetooth is switched off (when the headset is switched on). Conversely, the headset immediately switches back to Bluetooth when you disconnect the cable (when the headset is switched on). Note point "Using the supplied headphone cable" in the help guide: https://helpguide.sony.net/mdr/2984/v1/en/contents/TP1001856898.html

Yes, these headphones support multipoint connectivity, which means you can pair them with multiple devices and seamlessly switch between them. They offer a multi-point and auto-switch function that makes it easy to switch between devices.