Adam AX7's are excellent nearfield monitors. They do not lack quality low end, for sure.
The first thing I think when I hear your complaint is, are they somehow out-of-phase.
I think it's not possible to have them play out-of-phase because they connect with balanced XLRs (unless your cables are wired out-of-phase). So that is unlikely but possible. BTW X7s are linear to 42 Hz, that does not mean they don't reproduce lower frequencies but they start to fall off @42 Hz.
Your acoustic listening environment (your room) may have some issues. Does your DAW have a frequency generator plugin? Sweep down and see where the low end starts to disappear. Try that exercise panned left, then right, then together. Out-of-phase wiring will be very obvious. Try moving them to a different spot in the room. Do you have another set of speakers to compare? That would be helpful in diagnosing what is going on.
Finally, call Adam customer support. I believe they carry a 6-year warranty and the support is top notch.
Good luck, I would love to know the outcome. I am a very satisfied Adam AX7 owner.... I thought you should know.