Since purchasing a center channel several weeks ago, I am finding that I am having difficulty understanding dialog. I am using Mirage Omnisat V2 speakers and CC with a Def Tech Sub. The main speakers are set with a crossover of 80 and the CC at 100, all speakers set to small. I didn't seem to have this problem when I was running a 2.1 system. What adjustments do you think I should work with? I've considered buying the Radio Shack SPL meter, but didn't know if it was worth the price of that and a test disk for the very few times they would be used.

If you haven't calibrated, it's extremely likely that the center channel needs to be adjusted up. I'd recommend getting an SPL meter - you can use it and the 1070's internal test tones to get the system adjusted properly. It's an extremely important step with multichannel systems.