I don't think it will work. If you use 4 of 5 analog outputs from your Oppo DVD player, you will have the DVD player set to 5.1 or Dolby Digital output in order to get any sound from the L&R rear/surround output jacks. This will also cause the discrete center channel information to go to the center channel output, which you don't have connected to anything. You will be missing at least one 5th of the discrete information (all of the center channel content) from your DVDs.
I'm guessing that in order to use anything less than 5 channels of output from you Oppo, you will have to set the output mode to PCM or stereo. Then, you will likely only get output from the L&R front analog outputs.
I'm guessing that in order to use anything less than 5 channels of output from you Oppo, you will have to set the output mode to PCM or stereo. Then, you will likely only get output from the L&R front analog outputs.