That should work fine. Dynaudio make superb speakers. Their waterfalls are superbly clean and free of resonance - you will indeed need a good sub. The C1 midrange is not quite as perfect as the C4 but given you listen nearfield so I think the C1 will still sound much better. If you have a small room you will want the 300 otherwise get the 500 and your done....
Dynaudio sub with C1's
I was wondering if a Dyn sub with the C1's would sound similar to the C4's as far as the bass is concerned? For me there is something special regarding the Dyn bass. I listen near field and as much as I love the C4's they are too large for my listening area. I've demoed the C2's in my home and they are the largest I can go but still there isn't quite enough bass. Currently I use a Rel B3 (I don't have a sub out) and although the bass is very good to me it sounds a little slow for the Dyn's.