Quote Originally Posted by ultraviolet View Post
I tried a pulse transformer on PC spdif output to DAC earlier and I have to report that in my system it seemed to make absolutely no difference to the sound, which was a shame. Transformer was free though so not lost anything I guess.

Just waiting for new op amp to arrive to try out on DAC output now. .
I found replacing the JRC4558 with LM4562MA made a vast improvement to the sound.