Trying to maximize bass response ......

I've a system set up on a 13x19x9 ft room and have optomized set up (considering all of the variables and domestic no-no's). Referenced to a 1k and 200k tone using a Stereophile disc and RS meter, I have a fairly flat response to 32hz and a sharp fall off thereafter EXCEPT for a sharp dip at 50 and 40 hz (8 and 6db respectively).

I would like to fill in the 40/50hz null and would consider filling in the bottom octave by using a sub if it wouldn't end up with a sharp increase at 32 hz.

BTW the 40-50 hz drop out is definately room related - its there with panels and cones and pretty much independent of set up on the short wall and location of listening position. Long wall set up is not an option.

Any suggestions will be appreciated including those suggesting that I should just forget it and enjoy what I've got.

TIA