I don't fully understand your setup. If you're using an Oppo as an analog source, it should be a 105, not a 103. A processor with bypass would give you the best of both worlds. The front LR of surround could use your current stereo setup with the surround channels from a processor going directly to amps.
In my setup, output from DirecTV HD-DVR goes via HDMI to an Oppo 105 connected via HDMI to a Cary Cinema 11a processor. Stereo goes from the Cary to a Parasound JC-2 BP, surround directly to amps. The JC-2 is shared with an Ayre C-5xeMP and JC-3 phono stage. The Cary is shared by a Sony XA5400ES. For surround, the JC-2 BP provides unity gain and the Cary controls level. For stereo, the Cary and subs are out of the loop. I have used this scheme with the Oppo 105 serving as both source and processor, but I wanted mch DSD from the Sony that requires HDMI and a processor that can accept mch DSD.
db
In my setup, output from DirecTV HD-DVR goes via HDMI to an Oppo 105 connected via HDMI to a Cary Cinema 11a processor. Stereo goes from the Cary to a Parasound JC-2 BP, surround directly to amps. The JC-2 is shared with an Ayre C-5xeMP and JC-3 phono stage. The Cary is shared by a Sony XA5400ES. For surround, the JC-2 BP provides unity gain and the Cary controls level. For stereo, the Cary and subs are out of the loop. I have used this scheme with the Oppo 105 serving as both source and processor, but I wanted mch DSD from the Sony that requires HDMI and a processor that can accept mch DSD.
db