I have an older model, and they are sensitive to placement in the room.
They are pretty easy to drive though, and I have been through 5 different amps, with 1 failing after 10+ years, and 2 other temporary jobs, and a couple of tube amps.
I would review the set up instructions on the web site, and/or hit the Vandy forum.
If you can try an intimate what is bugging you, that could possibly help to ameliorate the cause.