Joint stereo? Try the opposite of however its set now. Increase the bitpool and maxbitpool settings too. You can use one of those config apps
http://www.touchxperience.com/en/adv...tion-tool.html
That one is the one I use. Some of the raw registry keys are below, from XDA...
Improve BT A2DP sound quality:
[HKLM/Software/Microsoft/Bluetooth/A2DP/Settings]
Add new dword, Value name=BitPool; Value data=48 (Decimal)
Modify, Value name=UseJointStereo; Value data=0 (Decimal, Originally 1)
For BitPool:
Microsoft suggests the following bitpool values for optimal buffer sizes.
30 - Low audio quality
40 - Medium audio quality
48 - High audio quality
58 - Excellent audio quality
Chose one you like. I think 48 is good enough.
For UseJointStereo: use 0 instead of 1, then you got the real stereo.