Good answer, EFSIII. I don't know that I can add much to it, as you covered the main technical reasons to get a sub.

I was very satisfied with the performance of my speakers for a year and a half without a sub. Since your mains look like they can reach a bit lower than mine, you are probably in a similar situation.

One thing that prompted me to take the plunge and add a sub was DVD-Audio -- without a sub or bass management to allow the LFE channel to be redirected to large mains, that channel is lost entirely. Several discs ended up sounding noticeably weaker as DVD-A than as DTS or DD (Blue Man Group, for example). Once I got a sub, though, I was glad I had it. Not only does it make all the difference with DVD-A, but it also does reveal the deep bass hiding in some DVD's. There have only been a few instances where I noticed some extra oomph in TV watching (a couple times on CSI reruns, as I recall). It is a little more noticeable on music, but it's on movies that it can really make its presence known.

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