Unlikely that the speakers changed. What changed was your perception, or possibly your settings on your receiver.It's a Marantz nr1609. Now I'm listening to it just fine at 50. That's weird. I don't know why. I've had for 1.5 years, only using it a few hours sometimes on weekends. Maybe the new speakers needed to be broken in.
I just like the idea of a stereo. I'm not really into headphones.
In that location you have three problems with the sound. First, the speakers are too close together for stereo separation. Second, the shelving is creating a resonant cavity that is likely disturbing the bass frequency response. Third, the tweeters are above ear level and not aimed properly at your ears.
Add number four, from that location the speakers don't reflect off the side walls in a controlled fashion for optimal imaging. Maybe add five, they are at the extreme far end of the room from you where proportionally more of the sound reaching you is reflected/indirect, particularly off the ceiling.
If you can mount them on the walls or set them on shelving/desk nearer to you at approximately ear level that will improve the sound. The corner placement of the desk that @Zorba922 suggested is a good option for a small rectangular room because it allows you to spread them out horizontally and also redirects the strong early lateral reflections away from your listening position while giving you stereo separation and also stimulating different frequencies of resonant room modes in the bass region for smoother bass response.
In addition to the excellent suggestions you already received, there's one more option if you must keep them in the closet.
Slide both of the closet doors to the middle of the opening and put the right speaker on the right side of the closet (assuming you have shelves on both ends of the closet that are similar in height). Turn the speakers on their tops with the tweeters on the bottom to bring the tweeters closer to ear level, and place the left/right speakers laterally centered in each of the left/right openings between the closet doors and the door frame for maximal clearance and widest unimpaired dispersion of the off-axis radiated sound from each speaker. Place the speakers toward the front surface of the shelf (maybe 1" back from the edge) so that the tweeters can radiate downward past the front edge of the shelf. You probably also want to put a towel or shelving paper on the shelf to protect the finish on the speakers.
The best way to figure out room acoustics is to experiment. All of the advice you got is worthless if you don't try it.