I have a way to make the Oppo into an excellent digital transport. However, it's not for the technically challenged.
I am using the Oppo 981. It is the model with the Faroujda video chip that plays CD, SACD and DVD-Audio.
My small add-in board listens in on the digital words sent to the onboard DAC chip. It resamples everything using a low-jitter clock oscillator. I have it configured to convert everything to 24/96 PCM sample rate. Everything means 44.1 CD, SACD, and all sample rates of DVD-Audio. It also bypasses the silly restrictions on the player's digital output connectors. Now I can listen to SACD and DVD-A using my high end DAC.
No need to spend thousands on a digital transport. It would be nice to be able to use the Stereophile lab test gear on the output.
The board has two low-jitter oscillators, a 27MHz osc for the Oppo DVD chip and the Cirrus Logic resampler chip, and a 24.7MHz osc for the Cirrus Logic SPDIF chip.
See the complete explanation in this long thread at DIY Audio dot com:
www dot diyaudio dot com/forums/showthread.php?s=&threadid=95972