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.

If you only have the 2 anamolies, you might consider the Rives PARC. At the very list, I would talk to Richard as he has shown himself to be very approachable. BTW, he also owns Talon now, so he should be able to tell you pretty definitively whether the PARC or a sub would be best.
I have read somewhere ("Listener" I think) that the RS meter is NOT flat and might be the cause for the dips and peaks in your measurments. How does your system sound?
That's not bad at all considering the meter isn't all that accurate. You must be sitting in a spot where these frequencies cancel. Move things about.

I believe the parc is only for reducing, not boosting to fill in.
The RS meter is not accurate in the lower bass frequencies. Usually it measures low in a curve moving up to flat at or above 100hz. I have a correction chart and I've also used the Rives disc corrected for the RS errors. The dip is still there.

Actually the speakers sound excellent as situated - the bass is excellent without correction but I think it could be improved a tad, especially in the 20's and 40's. The 20's I know I would hear, but I'm not so sure about how much some lift in the 40's would help. I sure don't want boomy bass from too much energy in the 30's. The speakers presently subordinate themselves to the music so I'm leary of changing the balance by inserting a sub if I need to use a cross over.

I probably aught to give it up but I hate to stop so close to my 'audio goal'.
While flat is a worthy goal it is pretty much impossible to obtain in a room. Music is usually a series of impulses (notes) not test signals. I bet if you played a series of notes from 32 to 50Hz or above on a bass guitar you wouldn't perceive that 8 dB dip that you measure.
Not bad IMHO. You could boost the overall level with a sub and then use a PARC to flatten the peaks such that the nulls were less deep. I would not use a PARC or any EQ to enhance the nulls.

If you want to judge how bad it is then try Rebecca Pidgeon Spanish Harlem and see if the base line is clear.

These are the frequencies played 49 62 73 65 82 98 73 93 110 ...if the first note in the progression is too weak then you can get a feel for how much you are missing in music.
I once flattened the response curve in my room using a Behringer DEQ2496. Boy, did the sound suck. Even the Behringer instruction manual warned of this reaction!

I was happy to remove the EQ and enjoy my out-of-balance but musical frequency curve.