That doesn't look like a good foundation for bass.. Stock pads aren't very good for lowest bass and make for an excess amount of midbass. Closing the vents also tightens up the bass, as already has been said.
I've got an idea. Maybe we would put up descriptions of our materials, like Paxmate/Silverstone/Biplast? Because from what I've seen, looks like Biplast, for example, is different from Paxmate.
So, Biplast:
Black.
Looks like foamed bitumen, but is not sticky.
Gummy, if you compress it with some force, it won't unfold, just form and almost uniform mass.
About 50% of open cells, 50% of closed cells.
When looking from the top, almost all cells are open (at least in the top layer, 2-3 layers deeper there are cell walls)
Cells are 0.3-0.5 mm in diameter approximately.
1 square meter sheet weights about 100 grams (floor scales don't register it, quite light by hand, feels lighter than my phone actually).
Paxmate seems to be much less porous, so that's may be the reason I get good amount of bass even with white felt in place. Even excessive amount, if more than 3.5 bass ports are closed. And that's on Beyer pads, with their quite big interiors.
