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

I'm running Maggie 3.7i with Pass gear and the sound is fabulous. You may need more break in time my 3.7 were well over 300 hrs before the magic appeared. Also play with the placement I always favored tweeter in speakers toed in and 18" from side wall with 36" from back wall on mid bass side and 30" on tweeter side. 
Good luck

I should add when I first had 1.7 they came without the jumpers installed and had me worried as there were no highs like at the store so double check your jumper connections.

Size of room? Heavily damped (rugs, curtains, etc.) or not?  Position of speakers relative to walls, listening position?

I just wanted to add, make sure your banana plugs are not inserted too far. They can sometimes foul some wiring or reach the panel. Also take a flashlight and look at the wiring near the crossover and see if you see something disconnected. I seriously doubt both panels would be a problem but it is possible that a new guy mis-wired them.  

-PrimaLuna EVO 400 Monos


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WOW those monos are some power pack amplifiers, 
Built in same factor as Cayin, Spark Audio, High quality, 
Very surprised you are not getting higher fidelity in all ranges..
hummmm,. 
I was close to buying the LRS, until my tech geek stepped in to cancel the project, 
Said the LRS has 4 phms impedence, 86 db, not friendly to the Defy7,,**ok for string quartet**, well the purpose was for big full orchestra symphony,,
Tech: *Not going to happen,**.

Not sure if what he is hinting at has anything to do with your issues of faulty highs, no sparkle, shimmerings, dynamics in upper fq's..
Sorry to hear of  this venture into Magnepan. 

There  is a big faithful magnepan group here,,maybe one these Magnepan-ians
can *chime* in here and give us some  solutions to this roll off issues.
Good Luck