I'm in the process of assembling a reference level surround system. I have about 650-700 surround discs (SACD, DVD-A, DTS ETC) and thought it was about time I took it seriously. The equipment is OPPO 205, Parasound P7, two Pass Labs X250.8 amp's and two pair of Magnepan 3.7's with two Rel subs. Should I added some sort of decoder to generate a surround soundfield from two channel source material? I've been looking at the Involve decoder along with some vintage units. My concern is given the level of transparency on true surround sources I may not be satisfied on simulated surround material. Anybody have sn opinion or recommendation?