Not sure if it helps, but I use original Nokia BH 503 stereo bluetooth headset, and my phone lasts a while (4 hours of music playback, and rest of the day standby ) but in some songs I can hear a slowdown on music like i used on my old tape walkman. And using the same headset with my nokia 5800 on the same songs with no problem. I already used SoundBoost from SavageD but it didnt solved the slow playback over bt headset