Hiyas, I just ordered a BFD to eq my sub. Right now my sub out on my reciever is going to my bass shaker amp and my sub amp. Since the BFD is stereo I was thinking of using one channel for the sub and one channel for the bass shakers. Now the real question... How would you measure the vibrations from a bass shaker to eq it flat or to a house curve? Do I need to buy a sizemograph for measuring earth quakes? lol FYI I have 6 of the auro bass shakers (non-pro) mounted to the box spring mattres of my bed! The top mattres makes a nice filter so I don't get "voice in the butt" and gives the vibrations a more natural feeling.