Don't even know if their is a constant or general effect but I just spent a few hours fine tuning my setup. Right now I'm running 1 Velodyne Impact-10 (32Hz) and a Martin Logan Dynamo 500 (29Hz). I'm very satisfied with the bass response I get with those 2 and their blend is as good as I can get it without a dedicated EQ.
Anyways, cut to the chase, I put on my favorite 5.1 recording, Steven Wilson's "The Raven" on BD and when Luminol started, volume about -20dB, I was really impressed by the depth of the bass. Maybe 7-8 mins in, it really goes on overdrive. Up to today I really wouldn't turn the volume down but just now I jumped on the remote, first time I felt such good bass at my place.
So???
How much deeper can subs get with a good in room response, seems I gain some and it's not booming or anything like that, chest thumping bass.
Thanks