Bass issues,,,,will new speaker help?

I have the same issue. My dip improved (narrowed the troubled band width and decreased the magnitude of depth a a little) when I added a subwoofer, though still bothersome. It improved again (decreased dip magnitude a little more) when I added passive high-pass filters to my mains and reintegrated my subwoofer, though still -6dB. I hope to improve it once more when I add a second subwoofer.

Chad,

In general, the Cardas Rule is a general starting point for speaker and listener placement. From there you must move your speakers and listening position for optimum results. When you stand in the corner, you are hearing bass that is all bunched up and lumped into a room mode. Apparently you have positioned your listening chair into one of the rooms null points and the bass is canceling in that spot. You must move your chair forward and backwards until the bass is natural, then adjust toe-in and width to suit. Of course, there is a strong possibility that your speakers are not compatible with your room and no matter what you do the bass will never be correct, but you must move the chair and adjust the speakers' positioning to give them their best shot. When you say your bass sounds hollow in your listening seat, that is a red flag that the seat is positioned in a null spot. Try moving things around and let us know what happens.

make sure you have taken care of your first reflection point

Checked out the system pics. Nice. Very capable.

That side wall is panelling, right? You can fur that out 3-4", only supporting and nailing it at the edges of each sheet and place 2" 703/705 behind it. Rock wool with a burlap/cotton sheet to retain it from touching is a more available alternative. If it's an inside wall, it's even easier and might not have to furred out as much. Drywall, done the same way, works too. The whole wall could be a membrane trap. Might have to get a bit creative around the floor registers. Then, there's that T-bar ceiling. Let me think about that.

Check out the Sumiko Master Set. There are two or three threads discussing it on A'gon. You've got great equipment and this is a very small cost to get incredible results.

Dave