I second @sbank 's advice on using basstraps in the corners. In a square room, you will have a huge problem with standing waves, given your front-to-rear and side-to-side walls produce the same frequency standing wave.
You should also treat your first reflection points. You can identify those areas easily with the help of small self adhesive mirrors. Those areas you should use a combination of absorbers and diffusors.
You've spent quite a lot on your system, so it worth your while to spend a little on treatments. You can start small; get a single good quality basstrap and put it into a corner, and a couple of good quality diffusers/absobers and treat a single side wall. If you are happy with the results you expand the treatments.
You should also treat your first reflection points. You can identify those areas easily with the help of small self adhesive mirrors. Those areas you should use a combination of absorbers and diffusors.
You've spent quite a lot on your system, so it worth your while to spend a little on treatments. You can start small; get a single good quality basstrap and put it into a corner, and a couple of good quality diffusers/absobers and treat a single side wall. If you are happy with the results you expand the treatments.