2 subs?

If you were getting good performance before moving and the only thing that's changed is the room, you might try playing with your speaker location and set-up (toe-in) and your seating position. The new room is "the hand you are dealt" but if all else is the same, tis the different factor.
Suggest you try getting that a right as possible, before spending bucks on additional equipment.
Good luck!

2 are better ,it loads the room better but it doesn't sound as it would help your current problem. Raising the crossover points on the subs may well make things worse. It sounds like you are getting cancellation of frequencies due to room reflections. Do you have a lot of glass in your new listening room? Are most of the walls highly reflective?You might want to try to damp them. Get a computer program that shows where to place the speakers or try moving them around the room. Experiment with angling them inward so their tweeter axis cross just ahead of your listening position. Don't buy anything before you attempt to see what is wrong with the room.

Google 'room mode calculator' and look for the Harman International White Paper on multiple subs.
'evens out the sound' is not quite exact. 2 subs can be located to excite room modes differently and in that way 'even out' the sound. The 'peak' nodes of one are where the 'low nodes' from the other are. The result is 'even'. People that tell you you can 'equalize' the problems away are non-starters. Just like a successful business Location, Location, Location. If the subs are located both the same, say mid wall on opposite sides of the room, you may not benefit from doubles. But, if you can manage some asymetry you can perhaps work it out.
I have the good fortune to have a listening room with 8 walls and an asymetric vaulted ceiling. I have a single, corner loaded sub which provides mucho even bass and is both musical and good for HT. AND, as a bonus, it is not a megabuck sub, but a modest HSU research VTF-2/mk3.

Work with what you got, first, before doing anything drastic which may PO the significant other.

I'll check out the Vandersteen site to see how well it agrees with what I read at Harman.......

That is odd. Try adjusting the placement - you must have a nasty room modal suckout. How about PHASE - do you have left right or subwoofer out of PHASE!!!!

Those speaker drivers are a favorite for use in bass guitar amps and you have a BIG MAC driving them - the last thing one would expect is for them to sound thin.

If you can't eliminate the suckout by moving things or reeversing wires (PHASE) then you are going to need lots of bass trapping.

Just curious but do the two rooms in question have different ceiling heights?

I had a similar problem when I moved a pair of Druids from a room with a 9' ceiling to a room with cathedral ceiling.