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

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.

Not to be argumentative, but Maggies are NOT ribbon loudspeakers. Well, the tweeter in the 3.7i, 20.7i, and 30.7 is a ribbon driver, but all the rest of the Maggie line and all their drivers are planar-magnetics, not ribbons. A "ribbon" driver is a very specific thing (the diaphragm of the driver and the conductor that causes it to move are one in the same), not just any ol’ planar.

Calling Maggies a ribbon loudspeaker is like calling an electric bass a bass "guitar". Common (Steve Guttenberg regularly refers to Maggies as ribbons, and John Atkinson always calls his electric bass a bass guitar), and incorrect. ;-)

@bdp24 your point is well taken. The point I was trying to get across is that Maggies do not move air. They don’t have traditional drivers they move air. Hence, no persuasiveness in the sound. 
 

@charliech No high pass filter used. RELs were connected to amps with high level REL cables made by Kimber and later Analysis Plus to amp binding posts. Crossover was tuned to my Maggies and the room. It’s been a while since I had the Maggies in my system. But they were crossed likely at around 80-100Hz. 
 

I would also recommend getting the Mike Powell silver Ag Maggies upgrade and putting the 1.7i pairs on better stands.