I just did this for my brother's proceed/logan system. Get a decent receiver like a denon 2804 and use the center & rear amps as normal. For R&L, use the pre-amp outs from the receiver to any inputs in the integrated. Hook up the dvd to the receiver only for 5.1. If you use the dvd for stereo also, use it's rca outs to the integrated as a cd.
When watching movies, find a place to pre-set the volume on the integrated (75%?) and never move it. You will use the level adjustments on the receiver to match the center and rears to the front level of the integrated. After this, the volume on the receiver will control all 5 channels the same. Keep in mind that due to different amps, the volume may increase slightly differently but still can be adjusted by the level controls on the receiver.
When watching movies, find a place to pre-set the volume on the integrated (75%?) and never move it. You will use the level adjustments on the receiver to match the center and rears to the front level of the integrated. After this, the volume on the receiver will control all 5 channels the same. Keep in mind that due to different amps, the volume may increase slightly differently but still can be adjusted by the level controls on the receiver.