So there was the last word...and then there's this last word.
Last week, shortly after my post...I found there was a static/something loose sound emanating from the front passenger side. I thought I was going crazy because it would appear and then disappear.
After a few days and a friend confirming the sound...I drove it right into the dealership and said there was something wrong.
Went out for a drive with a technician who was pretty awesome in trying to find the problem.
MURPHY's law kicked in - SOUND never appeared in 20 mins of driving!!! Either way, he fiddled around with some sections of plastic.
I then started asking him about the sound quality - he fiddled around with the Y-cable and the aux cable. I booked another appointment and he assured me he would get to the bottom of it.
Dropped it off this morning. Picked it up this afternoon.
Turns out - the main issue was a faulty Y-cable. THey also replaced the aux-usb jack just as a precaution.
And what have I discovered? Sound is marginally better than what I recall it being. Much thanks to the technician for figuring all this out. The static noise thing I kept on hearing was probably caused by the Y-cable and aux jack too because it hasn't come back!
So to FINALLY (hopefully) conclude this saga....
The sound is definitely worse than the old E90 system but still much better than it was when I first go the F30. Thank god.
This is really a pointless thread because my issue wasn't 100% resolved but I'd like to point out that there are good people out there in the BMW world who actually give a shit and will take the time to figure out what's wrong. Much thanks and props to Dave Lee at Parkview BMW for his help.