Magnepan 3.7 - 3.7i owners need help please


Hello, I have owned a pair of Magnepan 3.6r's for quite some time. I was assured that the 3.7i's were a big step in sonic improvement over the 3.6r's. So, I went and bought a brand new pair of 3.7i's. Got them home, set them up, and have approximately 20 hours of play on them.

I am using the exact same equipment as I had with the 3.6r's which is a Sanders Magtech amp, a Benchmark 3 hgc dac, and the exact same decent quality cabling. The 3.6r's had a partial external crossover and I was bi-wiring. The 3.7i's do not have anything but a single pair of binding posts, so I am using the exact same speaker cable but not a bi-wire version.

What I have noticed it that they definitely do not have the depth, spatial characteristics, or openess of the 3.6r's. They do however have maybe a more predominant midrange but, at the sacrifice of the midrange being bloated or muddled at moderate volume levels. I have noticed that the 3.7i's have sort of a filter membrane behind the midrange section which my 3.6r's did not. Maybe a smaller rear dipole radiation pattern? The bass is also lacking compared to the bass response of the 3.6r's

The Dealer said they may need more break in to loosen the mylar. However if that were the case, the midrange would get worse, but thembass may get better. The passive crossovers may need some more break in time, but to be honest, i'm skeptical about all of it!

So, anyone out there that can offer some insight would be greatly appreciated. I am just a working class hero with limited financial resources. I cant afford to spend a large sum of money for something no returnable, and go backwards with disappointment. Needless to say I did not get much sleep last night. Might need a prescription for xanax at this point!
 Thanks, Steve.. 
sfrounds
Not to say the magtech isn't "good power" but maybe an older Krell (fpb series?) or something like it would be a better match.  Good luck.
Sorry to hear you're not ecstatic about your 3.7s. I have owned the 3.6Rs and the 3.7s with the Sanders amp although with a Hovland HP 100 preamp. After break in I found the 3.7s more open and dynamic with a more detailed soundstage. As others have commented break-in is so essential. Keep the faith. 
After you've done your break in, if you are still not happy with the sound, I would first experiment with placement of the speakers and toe in.  Like any fine speaker, placement is everything and they might end up being placed a fair amount different in your room than the older pair.  Put two strips of painters tape on the floor and mark them in inches with a pen and proceed to move the speakers an inch or two (at the most) forward and back until you hear an overall improvement compared to other positions.  Then experiment with toe in. As a dealer I find that even long term audio buyers/audiophiles do NOT really know how to precisely set up their speakers to make them sound their best.  If you are unsure of your competence in this, please call your dealer your bought them from and ask them if they would do it for you.  Most will gladly oblige, often at no cost since you just spent a bundle on the speakers with them.  Of course, if you didn't buy them new from a dealer, then you may have to pay someone to do this, but if the person is knowledgable and practiced at speaker set up, believe me, it will be worth paying for a couple of hours or so of their time. Good luck!
Please examine the book Get Better Sound by Jim Smith, who worked for Magnepan for many years, who has provided some further guidelines for speaker placement that may lead to large sonic breakthroughs for you.  Book is very modest in cost, can call 1-770-777-2095 to purchase direct from Quarter Notes Press
I  spent many years with MGIIIs then upgraded to the 3.7s (not i) and they took several hundred hours to catch up to the IIIs.  Your amp is excellent, I use the Magtech with my 20.7s and would NEVER switch. Read the Magtech reviews on Rogers website, one of them was done at my house with my 20.7s.  One suggestion that I will +1 on is to get Mye stands, the 3.7s really benefit from the additional stiffness from the Mye stands.  Another tweek that I found is to use a tube pre-amp in front of the Magtech, I started with a MC 2300 and NOS Mullard 4004s in the driver stage, and now use the MC 1100 with the same Mullards, a truely perfect combination!