Oppo 203 setup/tweaks

I assume that the OP is not using an external DAC?

As do I since the filter selection has no relevance for the digital outputs.

My experience with the 203 as with the 105 is with its own internal DAC where it is a AKM (Japanese) and Sabre respectively.  With 4 of the digital filters the 203 was good but did not come up to the 105 in audio performance, but, on the 5th (super slow) I was surprised, it surpassed the 105.  A more natural and open sound, more harmonic structure and texture.  In both cases I am using the internal digital volume controls and connecting direct to the power amp.  In bottom end strength the 203 was no stronger than the 105 and maybe slightly less-not really sure.  Both are good, but, not the end all in bottom end strength.

Hey, what do you mean by "but, on the 5th (super slow)", is it an option ?

what digital filter settings..........

If you're using an Oppo 203, the best upgrade you can make - and the first place you should look - is to replace the switching power supply (SPS) with a linear power supply (LPS).  It's a 15 minute direct swap with a screwdriver and no "tweak" will come close to the upgrade that an LPS will make in performance across the board, whether you're using the analog outputs, digital outputs, or using it for movies.