Can my room support the Dynaudio C4s?

I think you are pushing it. At the very least, I'd recommend extensive room conditioning treatments. I had mine in a 15' x 21' x 7 room and found them very fatiquing until I added eight GIK 244 panels to my room. I've since moved on to speakers better suited to my room size. Also, I found the C4's to sound their best at high volume levels, which is another reason I sold them.

Make a dealer work for you. Get one to give you an in home demo.

IMHO, for your room size I think the C4s are too much. The C1s, Sonus faber Auditor Ms or Joseph Audio Pulsars would be perfect for that room size. Use a REL sub base system (G2) for the lower octaves.

Can my room support the Dynaudio C4s?...NO,too much speaker

Great question. My first gut feeling is no but were you considering original C4's or the new MKII? I ask because the MKII sounds so much better at lower volumes when compared to the originals which might work. Like Pdreher mentioned the originals sound the best at higher listening levels. That being said I am assuming you would be placing the speakers on the short 15' wall.

I base this info on the fact I had origianl C1's and have since upgraded to the C1 Signature in Mocha. I also have a Rel B3 sub. Ideally if possible an in home demo would be way to go.