[What size sub]

I currently have the RP-280f speakers, and would like to add a Klipsch subwoofer to my system.  I mainly listen to 2 channel stereo, but would like to try out a movie with the system.  My question, how do I determine if I should go with a 12 inch or 15 inch sub.  Any help would be appreciated...

 

latts

[Klipsch RP-280f boomy base]

Due to my limited space in my current room, I need to put the speakers almost against the wall.  This cause unwanted boomy base on some tracks.  Is there anything I can do to remedy this?  Can I put some damping material behind the speakers near the port to help with my problem?  Any thought/suggestions are appreciated...

 

Frank

[Integrated Amp suggestions]

If you have an opportunity, listen to the Rogue Audio Cronus Magnum II.  It's an amazing amp...