Rrog may be right about the speakers being too big for the room. I have a 12'x13 room and fought similar problems until I got smaller full range single driver speakers.
Having said that I recommend GIK Acoustics. They took a sketch of my room and suggested products to treat the room. I ended up with 2 corner traps behind rhe speakers and 2 panels behind me. For me it was the combo of treating the room and smaller speakers that did it. Just treating may work for you and the Vandys.
Having said that I recommend GIK Acoustics. They took a sketch of my room and suggested products to treat the room. I ended up with 2 corner traps behind rhe speakers and 2 panels behind me. For me it was the combo of treating the room and smaller speakers that did it. Just treating may work for you and the Vandys.