OP,
I pondered both the 203 and 205; and, I'm glad I went with the 205. It has a usb DAC, which allows me to play music stored in my computer's music library, from mp3 to 24/192, through my home theatre speakers. In experiments between this method of delivery to home theatre speakers and Airplay to home theatre speakers, there is no doubt about the usb DAC sounding best; and, in fact, this means of music enjoyment rivals my use of the 205 for SACD playback, even playing lowly AAC files. I now find myself using the 205 more for its usb DAC function than for its disc playback function. BTW, since your receiver only has S/PDIF digital inputs from which you can enjoy 5.1, you will not be able to play SACDs, since no SACD player delivers stereo or multi-channel SACD from its IEC958 or Optical S/PDIF outputs. You will only be able to enjoy SACD from the players RCA outputs to your receiver's RCA inputs, which in your case means stereo only SACD. If you buy a new surround sound receiver it will have an HDMI input which can be connected to the OPPOs HDMI output for multi-channel SACD pleasure. And, using HDMI connection there is no reason for the 205, unless you want a great DAC. You could instead buy a Sony UBP-X800 for about $300 and get about the same functionality as the OPPO 203, which would save you about $300 you could apply to a newer HDMI surround sound receiver to be able to enjoy multi-channel SACD, as well as stereo SACD. Do remember however the Sony has no RCA output, meaning if you keep your current receiver you will not be able to even enjoy stereo SACD.