The extreme sound damping with alubutyl (first layer) and sound foam (second layer) ...
- inner doors
- door cards
- woofer cases
- upfront speaker frames
... plus the upgrade from Infinity coax speakers to a 3-way 4-channel Hertz MP165.3 Pro system (plus mini subwoofer) lifted my sound to NEXT LEVEL.
Was it necessary? Not really, but it was on my bucket list, just like the PCCM+
The doors make the most satisfying sound now, when they fall into the lock.