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

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.

Okay, little update here...and this is for MY particular ROOM.  I think I've solved my situation, and posting in case it helps any of you.  I have a small room, and had the tweeters on the inside all this time, figuring it was the best plan with my little space. WRONG BRIAN!!!  I moved them to the outer edges, with slightly more toe in, and the difference is NOT subtle!!  Beautiful highs, openness, and imaging.  Plus it spread the music on a wider stage, with no loss of excellent imaging.  It's actually more focused in a real stage way, and as it was with my previous set ups. I'm now pretty damned happy, as set up the other way, they sounded like they were playing in their cardboard boxes!!!  So there you have it.  Your room may vary, but try what I did if issues, and remember to tow em in well. Ahhhh.  Back to Maggie May Bliss!

@trumpetbri Glad to hear it! Maggie’s are glorious. Anyone who says they are inaccurate is delusional .

@kingbarbuda "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."

Can you elaborate how you connected your RELs to your system?  Did you just set the crossover on the subs?  If so, what did you set them to?  Did you do a high pass filtering on the 1.7s?  I have some 1.7is on order and want to have two subs as well and am trying to figure out the best way.  

Right now, I have MMGs and I'm using a Bluesound Node and it's sub out with a single sub (and its high pass filtering and low pass filtering) to connect everything, and it sounds pretty good to me.  But I want to have two subs with the 1.7s.  Thank you.