Cool, happy shopping. As an FYI, I'm guessing you'll find that playing with placement should help considerably.
In theory, a rectangular room is better than a square room for even bass response. Square rooms typically have more problems with peaks and nulls in response throughout the room. If you were sitting in a big peak position in your last room, that might explain the differences you are experiencing now if you are sitting in a flat or null response area.
Ideally, find a position that produces the smoothest response in your primary listening position. The SPL meter should help you with that considerably. If you want more help flattening response, take a look at the
free REW software to give you an idea how good/bad your response curve is in your primary listening position for different sub placement options. If you end up wanting to go to this level of detail, you'll need some more parts when you go shopping (mainly mini stereo plug to dual RCA converters to connect the SPL meter to your computer, pictured below).
