Is there a big difference or am I wasting money?

islandman is rite on. with a sub i cannot see what advantage you would gain. the r/l sound on films does not include much low bass material in first place. is the sub operating during 2 channel use? if not then one might justify the upgrade if indeed it is an upgrade as i am unfamiliar with spkrs. if i were you i would be more concerned about matching the spks tonality in midrange than squeezing out fractional amts of deep bass during rare soundtrack moments.

There will be some difference given the 804S' aluminum tweeter and Rocehell woofers but if I were going to upgrade, I'd buy the 803S which is much more balanced in terms of bass and overall presence.

I have the 803Ds for my mains and have listened to the 803S and 804S.

Thanks fellas. I do about 50/50 stereo and multi channel. I have no sub. I thought about the 803S but space and $$$$ is a consideration. Thanks again.

If you can't hear a big difference, then it is a waste of money.

Unless you go to the 803D, you're probably not going to get your money's worth. I went from the N804 to the 804S to the 803D and while the 804S was definitely better than the N804, it wasn't something that I felt made sense financially, but the 803D was.