I just tried something similar, but with PVC adapters + old socks + polyfill.



I wanted something easy to fill/unfill from inside.
Well I still have to remove the driver, but then I have direct access.

So far I just measured 3 states:
- driver free air
- driver in enclosure, but not in door, hole open just behind the driver
- driver in enclosure, but not in door, hole filled (not maximum possible but closed, but still pretty easy to blow through)



Now the enclosures are in doors so I'll make some more measurements.
I could try something much more blocking like glass/rock insulation.
Or even one of the standard AP from PE/scanspeak etc.
Do you think I'm on the right path?