I need a new sub for my system polk rm20. Right now I have a very old sony sa-wm40 sub and while many have said that its good, it seems like it doesn't have what im looking for. to me i hear more of the bass than feel it. looking for a sub for 250 or less that will rumble my seats when watching movies mainly. occassionally i will listen to music with it. any opinions on what to get thanks.