I don't know why I go ahead with these updates. There was nothing wrong with my audio but against better judgement I chose to accept the part of the recent Dell Update which included an update for the Qualcomm wifi & bluetooth. I should have put money on it messing up my audio because NOW my bluetooth headphones sound like a telephone from the 70's -- flat and distant -- and there are all these digital pops and clicks in the background whenever it plays any sound that weren't there before.
Audio is fine BTW with plugged in headphones.
Did you try un-pairing and re-pairing the BT headset (so its driver re-loads) ?