The last thing I need to get for my current system expansion is a sub. These are the ones for under $200 that it's been suggested I look at. Am I missing any? Any opinions on which of these to look at? It's for a small area 12' x 14'. I need to narrow the list. The ones suggested so far are, Sony SA-WM20 Sony SA-WM40 JBL PB10 Acoustic Research S108PS Acoustic Reseasch S112PS Jensen JS-1000A Polk PSW250 Thanks!