My New Magnepan 1.7i's sound dull and lifeless on the top end...why?


First time Magnepan owner - 5  days old 100+ burn-in hours on them
Associated Equipment:
-Denafrips Terminator Plus
-Holo Audio May KTE version
-Pass Labs X22 Pre-amp
-PrimaLuna EVO 400 Pre-amp
-Pass Labs XA100.8 Monos
-PrimaLuna EVO 400 Monos
-AntiCables interconnects and speaker cables
-Stock tweeter attenuator jumper replaced with AntiCables level 5 spade jumpers on the 1.7i's

My spectrum analyzer indicates both speakers highs are falling off beginning at 1.25K and are 9db down from 2.5K on
Been playing around with speaker placement and room treatments for 2 days now without any remediation. What am I missing? Suggestions appreciated.
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@bdp24 I haven’t watched that video, but I will. The post was the 1st thing I chucked, now my crossover is soldered onto my cables directly.
I have Mundorf Evo Supreme oils for the mids, Mundorf Supreme Silver oil for the Tweeter, Jantzen wax 12 gauge Coil inductor for the Bass, Neotech 14 gauge Solid OCC Copper for the internal wiring.... The speakers sound incredible, Jazz is just to die for.
One of the coolest surprises was Electronic music, which previously sounded like monkeys beating pots and pans on the speakers, is now one of the most detailed, crisp 3 dimensional sound I have heard on any speakers.
My friends call the Maggies "The Spaceship". EDM sounds like a mushroom trip, no distortion whatsoever.
Fantastic speakers, but the crossover upgrade is an absolute must in my opinion.
@yuviarora did you install the GR-Research Maggie upgrade or are the parts you mentioned above something you selected yourself, or was your upgrade obtained from someplace other than GR-Research and if so, where? I have a pair of 1.7i. Thanks!
@kingbarbuda I made the crossover myself, just upgraded the factory crossover, kept the values exactly the same.
You need 115.8uf total for the mid section (3x33uf+10uf+6.8uf), 10uf for the tweeter, and a 1.4mh inductor for the bass panel.
If you follow the existing layout, you can just build a crossover using the same layout. A schematic is also available online.
I had to build a box attached to the speakers in the back of the panel, I put my crossover inside it. You can go about doing it however you see fit.
I went with mundorfs because they are very highly rated boutique parts, build it well and build it once.
Changing the crossover is an absolute must on these speakers.

P.S. Just  watched GR research's video, and his  way of building the crossover is his own, but I can tell you this, the stock configuration after changing all the parts is not lacking in the least. Treble is beautiful, shimmers that are incredibly detailed and never harsh. Everything is in balance. 
I would put pictures up if I could, the crossover box looks very nice on the speakers, I have also done a stand upgrade in the back. Both are bolted into the stock frame.

Just updated my Account picture. You can see the crossover box there. 

I just bought a used pair of 1.7i speakers, in pristine condition and only 7 months old. I own a pair of .7s and wanted to upgrade. The 1.7i speakers sound bad. Dull, bassy, no high-frequency detail. I was hoping to get more low-end response, but I wasn’t expecting the dull, lifeless sound. I am very experienced in setting up Maggies. Magna Risers don’t help. Different amps don’t help. Tweeters in vs. out don’t help. Neither does moving the speakers and my listening chair help. I can get them optimized, but I can’t remove the shelf in the frequency response (about 5 or 6 dB starting in the midrange, so that the lower mids and bass are elevated). Is this how they sound? Is there a large variation from one pair to another? My .7s sound awesome in the same room with the same equipment.