I'm not convinced that his "High Performance" SPDIF mod would do anything for a transport with a properly functioning SPDIF output. He basically replaced his broken SPDIF output for one that works.
I played with flaky SPDIF decades ago and it can progressively degrade the audio quality to the point of minor distortion, major distortion, then intermittent static in the music and dropouts.
I was experimenting with very long SPDIF cables making them longer while audibly noticing the sound quality degrade. I used various lengths of RG6X coax which is 75 Ohm and more commonly used in low loss Cable TV (and satellite) applications but works fine for SPDIF. I was running a 5-Disc Adcom CD Player / Changer as a transport to an outboard DAC in another location in my room.
