Pre amp's for new Magnepan 1.7

I have no idea how it sounds, but the Emotiva may fit, and new, at that.
I think it is also 2.1 capable which helps when/if you want to add a sub.

http://emotiva.com/usp1.shtm

Another avenue which you didn't pursue would have been spending the money on the new amp, plus the preamp budget on a higher power integrated.
My brief experience with a Rotel RB1070 was that it lacked power, even on my MG-1s. With the 1.6s, it was inadequate.

I had my 1.7's delivered about three weeks ago....I am using an old Dyanco PAS-3x. They can be had on eBay for $200-300 all day. The amp is a McIntosh 2105. Morrow cables. Sounds great.

Thanks, I will keep a lookout for those recomendations.