You definitely need to do something about your placement of the Nightingales.
First off, that room with all those windows is going to be a pain in the neck to get the best out of those Nightingales.
You need some big, thick curtains on every window. and if that were me and that room was the only room I could put my equipment; I would definitely put up slotted Bamboo window blinds in every window, then the thick curtains over them. Again, the bamboo blinds with the roughly one inch slotted blinds, not the matchstick blinds.
Second, you need a few nice wool area rugs. Depending on the size of that room, you can cover most of that room with two or three 8' x 10" or smaller sized area rugs.
Three and just as important........ The Nightingales have no business whatsoever being placed so far out from the back wall. They shouldn't be no more than 12"-15" inches off the back wall. And they really sound their best and really open up when they are 8 - 9 feet apart from each other. I've had my Nightingales for over two years and that has been the ideal placement to get the best out them; in every room I have tried.
I learned the further out from the back wall you place them, the leaner the bass gets, the less punchy the bass dynamics are and the imaging suffers badly if they are not spread apart correctly.
I don't know how wide that room is, but I'm guessing placing the Nightingales only 10-12 inches from the sidewall will help, also. In wider rooms they sound their best 18"-23" from the side wall.
If it were me, I would move that table and those chairs to the other end of the room and give the Nightingales all the room they need.
The curtains and blinds would also block out the sun/UV rays from getting to the drivers on the Nightingales. UV rays over an extended period of time will dry out your drivers and the rubber surrounds on the drivers. It will also dry out the finish of the wood.
Clean them with something like Pledge Multi-Surface cleaner (no amonia or harsh chemicals.....it's made for cleaning matte/silk finishes and lacquer or clear finishes on furniture (don't get any on the drivers or rubber surround); dry off. Then follow that up with Pledge's Extra-Moisterizing formula (with Lemon Oil and don't get any on the drivers or rubber surround) and let that dry over a day or two. You'll be shocked at how gorgeous the finish looks! It's beautiful!
At their best, with proper placement, good power amp and a good pre amp; the Nightingales will be plenty punchy, dynamic, smooth and their imaging is 3D. You'll think there's someone playing little instruments all around you, while the main soundstage is directly in front of you. And make no mistake, they kick out some real nice bass, for their size. You'll be surprised how low they go and how the bass guitars just pump out at you.