VG, as suggested by the other posters, it is fruitless to pursue a test methodology in which you listen to a stereo signal with different L/R components. I just went through this experiment in the course of upgrading from a well broken in ESS Sabre DAC chip in stereo mode to a dual mono configuration in which the broken-in stereo chip was restrapped to produce one channel in mono, and a fresh mono DAC chip was added to handle the opposite channel. I wired the two chips at random so I would not know which channel belonged to which chip. As I had earlier determined that a long break-in was necessary to bring out the best in the ESS chip, I fully expected to hear a significant difference from L to R.
In practice, the upgrade to dual mono produced an immediate improvement in perceived performance of both channels, but I could not hear any difference between L and R performance. As the new chip(in whichever unidentified channel) progressed through the break-in cycle, it became obvious that the entire stereo presentation was improving, but still impossible to associate this improvement with either channel. This proved to me that the mind hears an inextricable complicity between L and R that cannot be unraveled. It has nothing to do with plastic v. silk, phasing, or the like.
In practice, the upgrade to dual mono produced an immediate improvement in perceived performance of both channels, but I could not hear any difference between L and R performance. As the new chip(in whichever unidentified channel) progressed through the break-in cycle, it became obvious that the entire stereo presentation was improving, but still impossible to associate this improvement with either channel. This proved to me that the mind hears an inextricable complicity between L and R that cannot be unraveled. It has nothing to do with plastic v. silk, phasing, or the like.