I'm going to buy a pair of speaker stands for my atoms for my apartment bedroom. I was wondering what the correct size of the top shelf should be.

I was looking at this, which is 6 x 6
http://www.racksandstands.com/Platea...B-7PT0097.html

and also at this, which is 5 x 5
http://www.racksandstands.com/Sanus-BF-31B-7SY0003.html

Just wondering what the norm is, thanks.