Am I deaf?

I just went through what might be a similar issue to what you may be hearing with Redbook CD.

 I had been using an Oppo-93 SPDIF out to my Yggdrasil Analog 2 with a Jorma Digital cable (RCA at Oppo, BNC at the Yggdrasil). I was never quite satisfied with the sound. It seemed to be somewhat mechanical, bleached, or lacking tonal densities, with the mid-bass sucked out, and an emphasis on the treble. From memory, I seemed to recall getting better overall quality sound when I was using a CAL Delta transport with a lesser DAC (CIA VDA-2) and cabling.

I had read the Oppo 93 had high jitter and knew that was a problem. I also speculated that something might be occurring with the PCM conversion as the clocks in the Oppo are a different frequency than a dedicated CD transport, and error correction methods (Reed-Solomon or something else) could differ.

On a whim, I tried another Blu-Ray player and heard a difference. That was enough to convince me to get a dedicated CD transport. I recently purchased an Atoll DR-200 Signature, and the sound is significantly better. Now, CDs sound more analog and fluid , tonal densities have improved, the mid-bass is back. The system “boogies” again!

I’d suggest you try another transport. Even as a simple experiment, another Blu-Ray or DVD player. Even better, would be trying a CD player or transport that uses a  dedicated 44.1 kHz clock.

Perhaps the problem is not with the Oppo as a transport, but eliminating it as a variable should yield some useful information. 

Does anyone know if there are any settings in the Oppo that I need to adjust?

One other small point. The digital out of the Oppo if never used before... May need breaking in, even though the player has been in use for years. Not so the digital out .Give it a few weeks of use. THEN see how they compare.
When I hooked up a used but new to me changer to digital RCA out .it SUCKED. (I have a feeling the over 20 year old player had never been used with digital out, ever) and was not good for at least a week of all day playing. But now it is just fine.

Ok but isn't the digital out on all the time whether it's connected or not?

Many/most players have a switch or menu item to turn it off if not in use. Left on, not in use adds a ton of spewed hash...