You take your 2 channel preamp, and hook your L/R speaker set up as usually. Then, using an "auxilary input" or "bypass/monitor/tape input", you connect the L/R "amp out's" from your AV pre/pro to the 2 channel preamp, using one of those inputs. You connect all the other C/LS/RS, etc, output's from your AV pre/pro to the other amp channels. So, when you listen to 2 channel, you simply have your CD player, Tuner, whatever, connected to your 2 channel pre, as usually, and no need for the AV pre/pro to be on or switched in. Then, when you do want movies/multichannel, you simply switch the pre/pro in from whatever "auxilary input" you have it connected to on your 2 channel preamp, engaging the front L/R channels. And of course, the other channels are running through the other amp channels you connect. Simple really