Sounds like the window regulator - common point of failure on BMW's in general, I believe (my previous car, X5, ate up 3 during the 3 years of ownership). Not a hard DIY, and as far as sound deadening goes, I've heard of people lining the inside of the door with Dynamat or equivalent.
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Then - E53, E85, E92, E82, F15, F80, G01
Now - F97, Macan S