Thanks for posting those graphs. They are quite telling. That said, now re-set your horizontal scale to stop at say 10Hz. Next set your vertical scale to display 5-6dB per division. Things will look more appropriate and we can start looking at what is going on. After the measurements at the seat, you will want to take some measurements 1-3' forward, back, left & right which will give us some insight as to what dimensions are causing the various peaks and dips. Hopefully we can find a location for the second SubMersive that helps fill in some of the recessions. The 65Hz issue looks very narrow. Don't get hung up on it. We hear trends more so than narrow notches, and I suspect that a little movement of the microphone will show that notch moving around some. If there are doors that are normally open or closed, be sure they are in the position you would most commonly listen in, as they can affect the response in surprising ways. As for not knowing the subs are on, I suspect the issue is the peaks in the bass response, especially the two near 50 & 90Hz. These will significantly skew your SPL readings with pink noise. Try setting the subwoofer about +6dB relative to the mains and the average level should be more appropriate. Finally, make sure you have ALL of your speakers set to small in your processor (which one do you have again?). I'm sure things will work out nicely and sound great, as there is plenty of room for the DSP-30 to help you with the response you have posted thus far. Of course adding the second subwoofer may provide some nice smoothing of the response, depending on the location you end up with.
Seaton Sound, Inc. email@example.com 773-290-8436