This model of Eq allows you to adjust the front 3 channels: left, center, and right channels, as well as output to a left & right sub if you desire.
Since he's using the 5.1 analog outputs on his DVD player to the Ranethe eq, the DVD player is doing all the decoding via it internal decoder and just sending the decoded analog signals through the eq then to the AVR. Just by reading your post, it sounds like this is how you have it set up, isn't it?
Again, you'll only be able to eq that one source, the dvd player, in this type set up, and you won't be able to eq the surround channels.
Again, Receiver designers, Bring back preamp outs and main in's! or at least stereo (of course analog) source tape loops!
Brad