My system is running nicely now. It is a Pioneer Elite VSX52TX, two dvd players and a vcr player for movies and cd's, a pair of Altec Lansing Santana's, 15in woof with a tweeter. (I think the woof is a 420A BiFlex) For center, a Sonus Faber Electra and a pair of Mission 772's in the rear. It works very well for music and for movies. I am wondering about a subwoofer. My Santana's do bass very well, would there be any gain in experience with a subwoofer, and if so, what would compliment the system? I see that most of the offered subwoofs are smaller than 15in. Or does size matter, in this respect?