Gregm: I didnt get your comment or what you mean by "normal" prices speakers.I run a pair of Revel Salon's and will be adding a pair of B15's to them(even though they are flat down to 18hz), even for speakers such as these powered subs can be a good thing if implemented correctly. I would do Subs and full range speakers together regardless. Having full range speakers just means your subs have less work to do and can be crossed over at a much lower frequency which is a good thing. At the same time(assuming were talking a powered sub)the amplifier driving the main speakers now can run limited bandwidth potentially and can improve dynamic headroom(and dynamics)to the main speakers. But anyway, having a pair of subs to put in the corners of the room behind the main sattelites can be a huge bang for the buck upgrade.
An example. Take a cymbal crash. Its handled mostly by the midrange and tweeter right? Wrong! A good hard cymbal crash/impact actually starts at around 15-20hz, no kidding. When I auditioned a pair of Revel B15's in conjunction with my Salon's I was floored at the remarkable difference. Midrange and treble also were greatly improved by the harmonic ability of the subs. It was a night and day difference even with $19k floorstanding speakers.
