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.

@bdp24 Yes. I meant “pecussiveness”. Autocorrect messing me up again.

My experience with Magnepans are my former 1.7i and the AXPONA tests of the LRS and the LRS+. I added a pair of REL T/9i subs to my Maggies and it made a world of difference. Not hard to dial in. But I think the addition of the subs and what kind of subs could be room dependent. I have thought about getting a pair of LRS+ just for kicks. I haven’t pulled the trigger on that yet though. Going to AXPONA at the end of the week. Maybe something will happen there. 

I just received a call from the hifi shop that my Maggie LRS+ speakers have arrived. I would say “finally” but it was only a three month wait, which is a rather big departure for me since I’ve always bought everything I own from stock. I’m not a very patient guy…


Immediately upon receiving the call I put my pair of original MMG’s up for sale on another site, at a price I hope someone long interested in a pair of Maggie’s but hesitant about taking a more substantial financial plunge will decide to buy. I mean $275 for a pair of speakers as good as these is a pretty good deal.  It’s worth a toe in the water at that price. 

 The audio press went fairly gaga over the original MMG model when it was first released, and if the equally gaga opinions currently being tossed out there for the LRS+ are even half accurate I’ll be a happy camper. The two brands of speakers that have consumed most of my interest and money over the years are Magnepan and Thiel. There’s more than just “something about them” that keeps me wanting one or the other. 

I pick up the speakers this coming Saturday. Woohoo!

I’ve high passed my 1.7is at 100hz with dual tekton 2x10 subs, rca inputs.

played around a bit with sub xover, volume and phase settings for room/placement.

Happy camper here..