OP, your room is large and deep and has a lot of openings to it. You must take these factors in account. It seems that your HT is placed to one side - placement can change alot (one speaker is near a corner and the other is next to a wide opening - your sound is in trouble already
). I would like to see a layout or drawing of your room configuration (including wide openings to other rooms) so we can get a real ideal of how much power it would take to fill this room with sound. You may not have to spend a dime
. Worst case scenerio would be having to buy a new receiver with pre-outs and a multi channel power amp (that is the best configuration though). What you are missing is dyanmics - that's why your room sounds "empty". Your room and your speakers are really the only to components that you "listen" to. Change your room - you will change your sound, and may save you a little cash in the process.