call me crazy, but after trying a number of regedits I noticed that I would get different results with same settings. I began to formalize as much a possible my start up procedures and found that with my phone and S9 headset, the following is true:

in regedit:
bitpool=58
maxbitrate=80
jointstereo=0
**no samplerate value**

start up procedure:

turn on the apache,

turn on the headphones and wait for approx 30 seconds (if you have them on your head you will hear a faint hissing when they first power up, then a faint click or pop and then no sound at all)

now start your music player (I use windows media and TCPMP) and play music.

If I stick to this procedure I never get drop outs/skipping, hissing or distortion.

Can others confirm this observation?