Looking at some in room and quasi anechoic FR measurements for the Nova it seems that the FR, dispersion characteristics and variation in output vs environment is highly variable.
There is no way that some effort in room placement would not duplicate exactly the differences in sound that others associate with amp/cable changes at no cost to you.
The Nova and B&Ws are both geared toward a non-neutral reproduction-voiced for a particular attractive sound that audiophiles favor. Nothing wrong with that. I think that the voicing makes speakers such as these highly room dependent, that's why asking 6 people what they sound like gets you 6 different answers.
You could lessen or redistribute the room treatment you have to address the problem or try the SF Lumina which has a better FR (@30 degrees) than the Nova.
It's a shame that you aren't satisfied for the price you paid.