I fixed the mediocre audio in the HK system
It made me sad that my most expensive vehicle had the worst sound system. My 2008 535xi has a Logic7 system that is beautifully balanced, warm, and bassy. My daughter's Kia has a Kenwood Android Auto/ Apple CarPlay head unit with Focal speakers and a Kicker mini box under the passenger seat. Even my wife's GLE350 with a Harmon Kardon system sounded way better than my Alfa.
Turns out it just needed a new sub. Not even a big one. In the factory location I had a JL Audio 8w3v3-4 sub and JX500/1D amp installed. It took a little bit of playing with the car's bass/mid/treble settings and the crossover, but I no longer have that exception in my head when I say i love everything about the car. It finally has the sound that it should have had from the factory and it fit in the factory sub location, so I didn't lose any cargo space and it looks 100% factory.
There is currently one downside, though. Because I removed the load from the subwoofer channel on the amp, I get an audio system malfunction on the dash. It thinks the sub is disconnected because the impedance of the high level input of the amp doesn't match the former speaker. Has anyone figured out how to either disable the check or trick the amp into thinking there's a load there?