I don't know about your current L/R speakers, but in general, the ambient noise is mixed to those channels. Sometimes you'll hear dialogue from characters slightly off-screen, but with a 3.0 setup you're going to hear most of the dialogue coming through the center.

Upgrading to SX6 will dramatically increase the overall sound quality, but unless you make some adjustments to your current setup, the ambient noise will continue to be overpowering, and will decrease your overall experience.

I have the SX6's with the matching center channel. I started off with only the L/R channels, and recently upgraded to the center channel, and I was a little shocked when I realized how much worse the experience was now that the bulk of the dialogue was going through the center.

But there's an easy fix for balance problems, and overall clarity. First, you're going to want to point your center channel slightly upwards, pointed towards the ceiling but not dramatically. Next, you're going to want to go into your receiver's settings and change the balance. For me, I get the best results when I set the frequency of the left and right channels a notch or two below the center. When I first got the center, the left and right were substantially higher, and you could barely make out the center channel. Play around with the settings, and see what works best.

The SX6's are bigger, and they're definitely going to sound a whole lot better. It's worth the investment, but first play around with the settings on your current setup to see if you can push out better results.

If you have any questions about the SX6's, feel free to shoot me a PM.

Good luck, and most important of all, enjoy!