The speaker EQ function basically adds a 6 db bass boost below whatever setting you have selected to compensate for your speakers rolloff. Your speakers rolloff at 27 hz which is pretty low. Adding the boost at 55 hz should provide some effect. I would do as Helson above suggests and listen without the EQ engaged at a decent volume and get the boost via the bass control. Try moving your speakers around the room to enhance the boundary effect if you desire more bass. Depending on how much of a bassaholic you are, even a small sub will greatly improve you satisfaction with your system for both music and movies. One of the great benefits is that the sub allows much more headroom to be available on your mains so your can play them louder without drawing as much power from the amps.