Interesting little program, rogue9... it must not use the regular BT stack or something, because when I run it, it does indeed route the audio to the headphones, but the sound is extremely tinny and scratchy.
Experimenting over the weekend, I discovered a way to make this work. After powering on the headphones, I have to go to the bluetooth settings, hold-tap the VOX340, and select "Set as wireless stereo". Then I repeat for "Set as hands free". Then it works. It seems so ridiculous that I have to do that
every time, if the profiles are already checked, but there you go. Any suggestions for making it automatic upon headphone power-on would be welcomed.
Thanks to radimus and rogue9 for your suggestions so far.