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?
ricred1
Adjusting the audio delay settings didn't help. According to Marantz and Oppo's tech support the problem is because I'm using two different amps. One to drive the main speakers and one for the center. 

How are the source and amps connected? Does the 2 channel preamp have a HT bypass input?

Then the Marantz front preouts connect to HT bypass input on the preamp and analog output of DAC connect to an input on Marantz, correct? If this is not correct, can you please describe the connections between the Marantz, preamp, Oppo, and DAC.
The Marantz is used to drive only the center channel and isn't connected to my preamp. I had it connected as follows: from projector to Marantz via HDMI, from Marantz to Oppo via HDMI, Oppo to my preamp via Optical cable. My DAC is connected to my preamp via  balanced cables.