[Chad.Wagner]

1. The MX135 does a good job of processing optical inputs from cable boxes. I am not sure if running to the Oppo 103 would be a big improvement if you have it wired that way. Moving to the 105 I think you would hear an improvement.
2. Since the MX135 can not decode Dolby TrueHD or DTS HD Master Audio, I think using the 103D/105D is definitely the way to go for Blue Rays, Tidal, Netflix, or DHCP rendering which both players can do.
3. You would definitely have an improvement running the TV HDMI through the Oppo!

I love the HDMI inputs and the other features the Oppo 103 and 105D offer!

Having the optical, coaxial and 2 channel USB digital inputs on the 105D with a better power supply and DAC, made it easy for me to upgrade from the 103 to the 105. When the 105D came out I could not resist. I pan to get the 205 when it becomes available.

I run the 105 direct to my McIntosh MC252 amps for my gym. The 105 has a bit better volume control then the 103 did. I have a Sonos feeding it digitally (soon to be upgraded to a Roon box) and feed an HDMI input from my cable box into the 105D. I find going through the MX119/MX135 improved the sound a bit because the volume control is better and you do not loos any resolution by using a digital volume control that is in the 103/105D at lower listening levels, but the 105D does do a good job.

I have the 105D connected to my Bryston SP3 for my home theater and 95 connected to a MX119 in the family room. I still use a Pioneer BDP-09FD connected to another MX119 in the great room. I have a MX135 in a box.