Placement of dual subwoofers...

One of the reasons I am asking is that my listening room does not allow to have subwoofers equa-distance from the listening position.

My setup includes mains that will go down to the mid 30s. The only reason for the sub is to add a little bit more info. They are crossed as low as possible, around 40hz.

Then you should be able to put those puppies anywhere they will give you the flattest overall bass response, assuming that is your goal. FWIW I like the idea Duke raised about the Geddes technique and I would try that first. Do you have an SPL meter and a disc w/ 1/3d octave test tones. Sure helps if you do.

As Newbee Stated: A source with 1/3d octave tones is most beneficial when setting up a sub/main system. The Stereophile Test CD 2 contains all three decades. Time alignment is ALWAYS critical. My Tact 2.2X allows placement of the subs in the corners of the room(which unloads them dramatically), delays the mains(time aligns), and equalizes the responses(within .5db). The realism is outstanding.