Re: How much room damping needed for quiet listening?
Al low frequencies the wavelengths are many metres long. However, what the port sees is a pressure build up as it pumps air so there would be a difference between a port facing the room and one facing the wall.
I'd say you've hit the nail on the head here. The amount of energy you need to absorb is a direct consequence of the amount you pump into the room. So less in, less bouncing around and less absorption needed. I think I'd hang fire on applying any more until after some serious listening; sounds to me like you've got it about right.
Alan A. Shaw
Harbeth Audio UK