I own the Oppo and feel it's grand for what it is. However, it is a $200 machine, thus the transport assembly cannot be too expensive and all other parts surrounding it must be cheap. I would not drop hundreds into a mod on this unit as it may fail in 2-3 years. Do the DAC thing (I mated an upgraded Assemblage 2.0 with mine) and experienced much better audio. If the Oppo dies, buy another.
Modify Oppo 980 or add External DAC?
Will adding an external DAC to an Oppo 980 bring the same type of audio improvement as internal mods?