I recently upgraded from the C2's to the C4's and can say although they are certainly a step up from the C2's, the C2's have an openness and sweetness that i have only heard from the c4's on occasions. Im hoping that the c4's just need a few more hours on them and Im working on some room treatments to help. They do need to be well away from the back wall so I would tend to agree with jkuc, 3.5x6m is way too small for C4's.
Dynaudio c1 vs dynaudio c4
I have a dynaudio c1 confidence the c4 is better?, my room hace 3,5 x 6 mts, mcintosh 601 amplifiers and ayon cd5s cdplayer