I have found that when it starts crackling/skipping while on spotify, if I press pause and then play after a couple seconds it clears it. Returns after a while tho. Also, it seemed to stop once I turned engine off but left key in. I now have a wireless dongle (which is excellent), thinking this might sort it but it still happens, just not as severe. I'll try the reset tomorrow. When someone finds a solution, please tell all so we can all get it done while we're on warranty (I have a 21 plate t6.1). Cheers all.