Default Bluetooth problem with headphones

Hi everybody,

I have problems with Bluetooth since the installation of the last CM11 (android 4.4.2) on my galaxy SIII, I have search everywhere but never find any working solution.

I explain, all the time i listen to music with my headphone Sennheiser MM550-X. it's working fine when there is no object between my Galaxy SIII and my headphone. BUT as soon as i put it in my pocket the music begin to lag, the same when i put the phone under my hand for example.

It was working perfect before with the original rom from Samsung.

i have already tried to
- Change the music app (now i use Poweramp pro)
- Change the size of the music buffer and the priority of the music in Poweramp
- Change the CPU strategy to Performance (works fine with the small lag problem when the phone is in sleep mode, but no effect with the bluetooth)
- Change the headphone with another from my wife , exactly the same problem

Does anybody have any solution ? is it possible to modify the settings of the cyanogenmod bluetooth ? change the blutooth apk ? or to amplify the bluetooth signal ?

Thx