First I should tell you that I have the SMS1 connected to the 990 through a balanced cable and 2 LMF1'S and 1 Earthquake Supernova MarkIV hooke up to it. I also have the analog eq goting to one of the inputs on my 990. My room is rectangler in shape 18w x 28l x 8h and opens to other areas which is why I need the extra bass.
I have one LMF1 located near the left front speaker and the other two subs located near the right surround so they are diagnal to each other and the ones near the right surround are in a corner.

I tried the auto setup first and it did an ok job but not perfect so after reading the book and some of the posts I attempted to do a manual adjustment.

I had a 5db dip at 30hz an another around 50hz I changed the crossover in the 990 to 60hz for all speakers ( I have Rocket RS750 sigs in front and for surrounds with the RC200 center) which helped then I fliped the polarity on all three subs now I have a flat line and I do mean flat from 16hz to 120hz before it starts to dip. I just didn't think that a real flat line was possible. I should mention that it is flat across 86db.

I zeroed out the crossover in the SMS1 and told it to optimize from 25-48hz which is where my speaker range is.

I then let the 990 do it's auto calibration which came up with sub at 28 feet and +5db.

It sounds great but now the dogs and wife are running for cover!

Merlin

- Sounds like the SMS-1 did the trick for you.