Windows 10 can _definitely_ do that (I do the exact same thing with bluetooth/wired headsets frequently; I'm "fairly" sure I used to do that on Windows 7 too -- I remember being quite amazed when my Ubuntu machine "finally" caught up and was able to do the same thing.)
In fact, I quite often start music playing on the laptop (chrome/Google Play Music) and then power up my bluetooth headset -- it initially uses eSCO when it routes the audio over (mono) and then switches to A2DP a few seconds later
Maybe the issue is something to do with the SW (chrome/firefox?) you use for GVoice? Or maybe there are some edge cases that I'm not triggering (in particular, a USB headset is effectively a new soundcard and not just an audio sink; I can completely believe windows is flaky with them especially with third party drivers)
In fact, I quite often start music playing on the laptop (chrome/Google Play Music) and then power up my bluetooth headset -- it initially uses eSCO when it routes the audio over (mono) and then switches to A2DP a few seconds later
Maybe the issue is something to do with the SW (chrome/firefox?) you use for GVoice? Or maybe there are some edge cases that I'm not triggering (in particular, a USB headset is effectively a new soundcard and not just an audio sink; I can completely believe windows is flaky with them especially with third party drivers)