This is my first post. My HT speakers are RF-82lls SW-308 and RB-51lls. My room is 20x20 but my sofa is in the middle approx 10 feet from speakers. My sub sounds great smooth deep and natural. But could us a little more output considering the room size. My question is would a second SW-308 give my more bottom or upgrading to one sw-310 be the way to go?