From my research, while the other Oppo's have better picture, the now discontinued Oppo 970 has the best CD sound of all the Oppo units, so upgrading to another Oppo unit is not a consideration.
I haven't considered modding my 970. That is an option I will look into.
I do not want to add an external Dac. If I consider adding a DAC I think I would go with a preamp and CDP down the road, or the new Benchmark DAC1-PRE, but it's to pricy for me at the present.
I was hopping Denon, Marantz, Cambridge, Pioneer, etc. had variable outputs. Do any of these or other DVD players have any?