Thanks guys for the response.

I just bought NAD 356BEE and Marantz CD 6005 paired with the M22s. My room is 9*18 and one side wall and front wall with openings. Right now I set the speakers with Cardas placement and it works fine. The bass is thin so a sub may be needed later on.
Any suggestions to improve the set up? Is Cardas placement good for my room?

Regarding AMP, I read an article to use AV receiver for surrounding and sub, but int-amp for front/main speakers. By doing so, you could enjoy the pure music while has the option to get home theater set. That could my my future path?