Dangelod,I have heard the C2's and I do own a pair of Dynaudio S5.4's..For my size room 13x21x8 vaulted the 5.4's are perfect..I also run double subs with them and it is perfect...I too am looking for the day I pick up a pair of C4's for more of that Dynaudio magic.C2s or 5.4's with 2 subs would be nice for your setup...
Also look into OCOS speaker wire for the Dyn's.They just shine with it ,and is also recommended by Dynaudio..
I use a triple run to my speakers...A good rule of thumb for OCOS wire is 8ohm (1 run),6ohm(2 run),4ohm(3 run)but it is also up to you ears and the sound you like.
Here is a quote form this person from a past forum:
Im a Dynaudio dealer so maybe I can offer a comparison as I listen to these on a daily basis.
The S5.4s are a true 3-way design utilizing the incredible Esotar2 tweeter. Very smooth and detailed and incredible bass output. These will play loud and not strain doing it. I usually represent it as an music lovers/reference home theater speaker.
The C2s are a step above in transparency top to bottom. I find the highs to have more extension, the mids to be more transparent and open, and the bass to be tight and responsive. It wont play as deep or loud as the 5.4s, but its a better music speaker IMO because of the increased resolution.
The C2s tend to disappear better than the 5.4s too. You can close your eyes and they transport you to the live event better. The Confidence line incorporates the DDC driver configuration which eliminates up to 70% of floor and ceiling reflections which can really help in some rooms. Though the drivers look similar, the Confidence drivers have a more robust motor structure, which coupled with the more exotic cabinet construction, contributes to an overall superior speaker.
However, both speakers are spectacular. Dynaudio uses very similar crossover points and driver technology between the lines so they all share the house sound. If you are building a reference 2-channel system, the C2s are better in my book. You might even consider the Sapphires which combine the transparency of the C2s with the low-end authority of the 5.4s.
Hope this helps.