I am trying to get my Sony WH-CH720N headphones to cooperate over Bluetooth with Linux (Ubuntu 24.04) but I am having the following trouble.
If I select the output device as "Headset", I get good sound quality, but the microphone is not used. Instead, my built-in laptop microphone is used.
A "Handsfree" microphone device seems to be available, but if I select it, the output device is switched to "Handsfree" as well. This makes the audio quality suffer greatly, as if it were sent through a phone call or something.
I attach a composite screenshot of the settings pages for the "Headset" and "Handsfree" options.
Changing the "Configuration" setting with "Headset" makes no difference.
Changing the "Configuration" setting with "Handsfree" is synchronised between the output and input device, and selecting the first option is not possible for some reason. Notably, the two configurations do sound different, in that one seems to allow more treble, while the other seems to allow more bass, but they're both terrible anyways.
Nota bene I had similar trouble over on Windows. On that system, the headset always sounded bad (i.e. there was no way for me to switch over to an equivalent of the no-mic "Headset" option), until I followed this guide to switch off a "Handsfree telephony" service.

 
    