Calibrate your Audyssey software using a calibration kit designed specifically to tune your home theater. I bought this for $550 from Magnolia last year to calibrate a Balanced Multi-EQ (sold). It is the DIY kit.
It comes with software and hardware parts and was used only one or two times. You don't need to pay to use the software unless you choose to store your data online and print charts.
See the DIY column in the product information detail linked below for specifics.