I just bought a velodyne sub at CC. This is my first home theater purchase so I do not have much to compare to. It is a chp 10 inch. The have a cht 12", cht 15", and a ct 15". How much difference is there between the models and should I upgrade while I have the year to do it. My current set up is below front surrounds Polk rt-5 ceneter Polk cs-245i rear surrounds Polk rt-25i and the 10" velodyne cht sub reviever Onkyo 595 Thanks for your time!!!