A year ago, I replaced my Polk PSW-505 by a Velodyne DLS-5000R and love it! A few days ago, I decided to put back my Polk to pair my Velodyne and imho, the two playing together just sound BADASS! Question: Does it mather if I don't use 2 similar subs? Should I buy another DLS-5000R or a 4000R? thanks!:)