To all who have submitted their comments--I really appreciate it. I now better understand why a sub is a good idea after it was pointed out that my Titans only go down to about 60hz. That in fact, was my main question, i.e. how do I know that adding a sub would really make a difference. But now that I better understand the limitations of my current speakers i see how adding the sub should make a noticable improvement. So I think tomorrow I may go out and get one. I won't spend a lot of money though and I don't want one that is too big. I saw a Yamaha yst-215 8 inch sub at Best Buy as an open item for around $100 so I'll probably check that out. Thanks again for all of the insight.