Which DVD player

The Onkyo SP1000 has significantly better build quality, sound, and UI/interface than the Marantz universal. Only thing it's missing is 480i over HDMI, but it sounds like you don't need that anyway if you're planning on upconverting at the player level.

"The players on audition are Arcam DV137, Rotel RDV1092, Marantz 9600 & Denon 3930. All 4 do not have significant difference in 2 channel or 5 channel audio."

??? Is your stereo up for the challenge of resolving the sonic differences between these players?