Thanks again for the help. I was mistaken a while back the other old Denon is not 3310 but the 3313 which doesn't have the EXT IN. The 1802 does have it but I'd rather just use the 3313 since its rated at 125 W/CH whereas the 1802 is only 80 W/CH. I guess I'll just use the 3313 to power the LR front speaker's and let the X3700H handle the remaining 9 ch.Not necessarily. I just set mine to the "CD" input, then set it to "pure direct" which bypasses all of the old audyssey adjustments, etc. Then set the volume to 0 dB (reference level.) After that, all of the volume adjustment, audyssey corrections, etc. is handled by the x4500h.
Both your 3310 and 1802 have the multichannel analog inputs (labelled "EXT IN" on the back.) Then you would need to set that AVR to the "multi channel in" setting and then "pure direct." But I don't know if the X3700h has a setup that will output the three front channels while running the rest. I think it only supports outputting either the mains or the second height channels.