The output stage can be modified with a choice of caps and resistors that would work with whatever downstream equipment you have in the signal path. I have modded a few Playstations with different caps in the output signal path, and obtained different results. Using the widely acclaimed Black Gate N or Sanyo OS-CON SC electrolytic caps seems to match up very well with tube amps where top end roll off could be a problem. I recently sold a modded unit with the Elna Silmic II caps in the output stage, as the buyer's tastes fit very well with the smooth treble response of the Elna Silmic II caps. He's using that unit with an SET amp and he is quite satisfied with that. It just comes down to personal preferences.
Have you also tried changing interconnect cables? That can largely influence the sound quality as well.