I believe this month's Stereophile has a sidebar about a Sony ES active preamp. It has 2 sets of 5.1 inputs and one set of 5.1 outputs. It apparently offers little more than balancing other channels to the front main speakers. Minimal circuitry with a supposed minimal affect on sound. It appears to be more of a "switch" than a preamp, though it apparently is not passive. I have found no info anywhere on the web unfortunately.
