Doxastitc

I just picked up a set of rvx-54's and as I'm installing them I noticed there's two speaker inputs- HF and LF. What's the difference?

I need some advice. I currently have a Velodyne impact mini sub and a Def. Tech. Mythos 3 center as the beginning of my home theater system. I found the XF-48 for $800 a pair, the RF-82 for $600 a pair and the RVX-54 for $500 a pair. Which would you go with? I like the sound of the XF-48 but I already have a sub. If I get those it would be like having 3 subs.... kind of overkill. Or maybe not. Maybe it would be totally awesome. I could isolate the sub frequencies to 40hz - 70 hz, just for the low-lows. And everything else would come through the XF-48s I like the RVX-54's because they would be a 100hz and above speaker. That complements my sub better. But I'm not sure they're better speakers. And I keep going back to the XF-48s. So, given I already have the center and sub, which would you recommend for the fronts?