Hi gandalf,
Both the Magnepan 1.7i and Dynaudio Confidence C2 are very good speakers that are somewhat inefficient, meaning they are likely to sound best with higher powered amps.
IMO, the CDA470 would be a good match with both of your speakers. I used a CDA440 with a VTL tube preamp on Magnepan 2.7qr and it was the best bass I've ever heard them produce. I now use D-Sonic M3-600-M class D monoblocks and know these outperform the CAD440 in my system, mainly in dynamics and an improved mid-range and treble.
There are also the top of the line D-Sonic M3-1500-M monoblocks ($2,550/pair) which may be the best solution for you. These mono-blocks received an excellent review from 6Moons that is linked below:
http://www.6moons.com/audioreviews/dsonic/1.html Overall, I would suggest trying the M3-1500M mono-blocks through their in-home trial program. I would certainly audition these before even considering anything more expensive than their price of $2,550/pair. However, I don't know your budget and while the D-Sonics are a great bargain and a great match for both your speakers, they're not exactly inexpensive..
Good luck,
Tim