Hello wemfan,
Both Loomis and Al above are correct, you can use your Oppo 105D as a preamp processor to do what you want. Here's how to do it:
1. Connect an HDMI cable from the output on your cable box to the HDMI input on the back of your Oppo. Note: this input is listed as "3. HDMI IN-Back" when you later use your Oppo remote "Input" button, located on the top of the remote between the red "Power" button and the disc drawer white "Open" button, to select the proper cable box source.
Once setup is complete, you'll be using the Oppo remote to control volume and the cable remote to select the channel.
2. Connect another HDMI cable from the "HDMI 1" output on the back of the Oppo to the HDMI input on your TV. Note: you'll also need to select the proper input on your TV. It's also important to use the HDMI 1 output on the Oppo because it's the only output that benefits from the Oppo's excellent Marvell QDEO video processor.
3. Connect a pair of XLR balanced audio cables from the left and right XLR "Stereo Outputs" on the back of the Oppo to the "CH 1" and "CH 3"
XLR inputs on your A-31 amp. For wiring simplicity, I suggest using CH 1 for the right channel/speaker and CH 3 for the left channel/speaker. Set the "Gain" knob to the middle 12:00 position and the "Balanced/Unbalanced" switch to the balanced position on both channel CH 1 and CH 3 inputs. Use speaker wire to connect the right LS50 to CH 1's speaker outputs and the left LS50 to CH 3's speaker outputs.
4. Connect a single RCA unbalanced cable from the "Center" output on the back of the Oppo to the "CH 2" RCA input on the A-31 amp. Set the "Gain" knob to the middle 12:00 position and the "Balanced/Unbalanced" switch to the unbalanced position on CH 2. Use speaker wire to connect the KEF center channel speaker to CH 2's speaker outputs.
If you want to add a sub, just connect a single RCA unbalanced cable from the "Subwoofer" output on the back of the Oppo to the sub's RCA input.
5. The final step is to use the Oppo's remote to navigate to the Audio Processing Setup Menu to optimize the audio configuration. This is the section in which you're able to match the relative volume of your speakers, indicate whether a center ch speaker and/or a sub is being utilized, set the crossover frequency for the sub and determine which speakers will have bass assistance from the sub and which will not. You can read all about this section beginning on page 63 of your Oppo manual.
I'm certain this setup will work well for you since I also use a Panasonic plasma, Oppo 105 (not a D version) and multiple amps in my combo 2-ch music and 5.4 HT system. The Oppo 105 are excellent serving as surround processors up to 7 channels with a sub or subs. There's no Atmos but all channels utilize high quality Saber dacs capable of up to 24 bit/192kHz hi-res playback.
Tim
Both Loomis and Al above are correct, you can use your Oppo 105D as a preamp processor to do what you want. Here's how to do it:
1. Connect an HDMI cable from the output on your cable box to the HDMI input on the back of your Oppo. Note: this input is listed as "3. HDMI IN-Back" when you later use your Oppo remote "Input" button, located on the top of the remote between the red "Power" button and the disc drawer white "Open" button, to select the proper cable box source.
Once setup is complete, you'll be using the Oppo remote to control volume and the cable remote to select the channel.
2. Connect another HDMI cable from the "HDMI 1" output on the back of the Oppo to the HDMI input on your TV. Note: you'll also need to select the proper input on your TV. It's also important to use the HDMI 1 output on the Oppo because it's the only output that benefits from the Oppo's excellent Marvell QDEO video processor.
3. Connect a pair of XLR balanced audio cables from the left and right XLR "Stereo Outputs" on the back of the Oppo to the "CH 1" and "CH 3"
XLR inputs on your A-31 amp. For wiring simplicity, I suggest using CH 1 for the right channel/speaker and CH 3 for the left channel/speaker. Set the "Gain" knob to the middle 12:00 position and the "Balanced/Unbalanced" switch to the balanced position on both channel CH 1 and CH 3 inputs. Use speaker wire to connect the right LS50 to CH 1's speaker outputs and the left LS50 to CH 3's speaker outputs.
4. Connect a single RCA unbalanced cable from the "Center" output on the back of the Oppo to the "CH 2" RCA input on the A-31 amp. Set the "Gain" knob to the middle 12:00 position and the "Balanced/Unbalanced" switch to the unbalanced position on CH 2. Use speaker wire to connect the KEF center channel speaker to CH 2's speaker outputs.
If you want to add a sub, just connect a single RCA unbalanced cable from the "Subwoofer" output on the back of the Oppo to the sub's RCA input.
5. The final step is to use the Oppo's remote to navigate to the Audio Processing Setup Menu to optimize the audio configuration. This is the section in which you're able to match the relative volume of your speakers, indicate whether a center ch speaker and/or a sub is being utilized, set the crossover frequency for the sub and determine which speakers will have bass assistance from the sub and which will not. You can read all about this section beginning on page 63 of your Oppo manual.
I'm certain this setup will work well for you since I also use a Panasonic plasma, Oppo 105 (not a D version) and multiple amps in my combo 2-ch music and 5.4 HT system. The Oppo 105 are excellent serving as surround processors up to 7 channels with a sub or subs. There's no Atmos but all channels utilize high quality Saber dacs capable of up to 24 bit/192kHz hi-res playback.
Tim