Wolf_garcia, regarding your comment:
The "put the sub in your listening spot" suggestion is ridiculous (but amusing) so ignore that one
You are simple incorrect. Placing the sub in the listening position and then walking/crawling across the room to find the place with the most even bass response, helps one find the place in his/her room that beside having an even bass response it is also the acoustic equivalent of the listing position, i.e. the interference pattern of the low waves in that place is very similar to the one in the listening position. The method is not ridiculous at all, in fact it is based on simple 3-dimentional Euclidian geometry.