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

@eatapc Hi. I am a former Maggie 1.7i owner. This is what I recommend:

1. Magnepans NEED subwoofers. They do. They are ribbon speakers with no air movement and no percussion. There is no slam. They need subwoofers. I added a pair of REL T/9i subs to my 1.7i and it revolutionized the sound. 
2. I agree the binding posts, fuse and jumper are steel plate garbage. I replaced the steel plate jumper and cheap fuse with Mike Powell’s silver upgrade. It’s a sliver humper and a silver tube replacing the fuse. Those changes greatly improved the top end. I am sure if you are handy enough and can replace the crossover and binding posts, more benefits will accrue. 
3. These Maggies need powerful solid state amps for regular driving, but also for headroom and dynamics. Schiit Vidars are insufficient. Amps like the Brystons and Pass Labs are good. 
I hope this was helpful. 

Hi Friends, 

So I am at about 250 or so hours with my new 1.7i's, and also experiencing the lack of highs, and sort of lifeless sound as well. Do they ever open up more, after more hours...or is this it?  🤔  They are quite slow sounding, and I have a McIntosh MC 252 driving them, on its 4 ohm Taps.  So weird. I'm  not used to Maggies sounding slow, as I've owned MG 12's in the past, along with. 5's, and these sound nothing like those.  So will these open more in time? Did the original post guy have any changes to his?  Really curious, and also wondering if I should start driving them hard and loud to get em to open shop.  Just don't know.  Thanks for any insight.  -Brian.

Did the original post guy have any changes to his? 

Yes, he had pushed the banana plug in too far and it was contacting elements. Your issue may be different. I didn't like my Mac 402 with my .7 Maggies. Much better with a Parasound A21 and a lively preamp. 

OP, this will answer some questions:

I’ve been a loyal Maggie owner for decades using 10s, 1.6s and 3.6s as my main speakers. I even bi-amped my 3.6s using a Pass Labs XVR -1 crossover. I moved on to YG Acoustics and couldn’t be happier. The YG’s are more accurate, neutral, detailed and musical.

I have no affiliation with GR, but found the video and measurements to be informative.