Adding Center Channel

I currently have my 2 channel providing the Audio for my projector. Unless I turn the volume up significantly the dialog is too low. I was told adding a inexpensive AV Receiver and center channel would help, so I did. I purchased a Marantz NR1607 and Monitor Audio Gold center channel. The NR1607 is used to drive the center channel only. The problem is I hear dialog through my main speakers before I hear it through the center channel. It almost sounds like an echo. I've tried everything and I can't solve the problem. Is it because I have two different amps(1 driving the main speakers and the AV receiver for the center channel)? I've contacted Marantz and Oppo via the phone and they couldn't resolve the issue. Any suggestions?