@chauncey
I’m not familiar with the details of so many products out there but being the owner of an Oppo 105-D I speak from my own experience- use something else if you want high quality sound reproduction. I used the Oppo for about 2 years- both as a disk player and a dac and I just grew tired of the glaring presentation.
I started trying/buying other DAC’s (PCM and R2R) and finally settled on the Aqua La Scala. My Aqua has I2S as well but I’m not using it. The manufacturers claim is that it is best when used in conjunction with their CD transport or their Streamer. I use SPDIF coax/BNC for my server to dac and AES/XLR from my streamer and I don’t feel I’m missing anything.
I’ve heard/read comments from others praising the I2S interface but it still seems to be the Wild West as it’s not a standardized interface. Some builders use it to interface between components within their product line but brand to brand interface leaves you hunting for component pin outs, custom cables and being at the mercy of how much effort the designers put into its integration. Bottom line- there are many excellent DAC’s and players that don’t require I2S to sound their best.