Several years ago, I built a down firing sub cabinet which I used as a coffee table in the living room. I found the bass response rather smooth as this sub was placed at about the center of the room, so away from the walls and that helped with the overall response.
Now, I have 3 more capable subs in cabinets which are located closer to walls or corners, and I experience an amplification of the bass frequencies in the same room as above due to room gain. As a matter of fact, I set the graphic EQ on the SR5011 to get the bass output at -4dB and also blocked one of the ports on all three cabinets to reduce the bass output amplitude. I haven't decided yet but I am looking forward to eventually getting the Dirac Live room correction EQ module to gain a better control on the overall room and bass response.
