You can plug the rear ports of the 5.3s with some foam or tube socks if need be--it can solve the problem(if there is one in your room) and it doesn't change the character of the speaker(I have done this with my 5.3s to great effect). In many rooms the 5.3 does fine 2ft. from the back wall without plugging the ports, but you always have the option. If you like them I wouldn't give up on them because of this--you should at least try them at home as it may not be an issue at all. Best of luck.
Tim
Tim