I said I'd report how the 596 worked with the 518, so here goes:

Bear in mind, I use the 518 only for jitter control, so I'm not using its sound-shaping capabilities.

Unlike the 500 MkII, I didn't see any improvement in sound for the 596 with the 518. With my 500 MkII, the 518 difference was significant and very positive. With the 596, I heard no difference at all.

This seems to imply that the 596 jitter is already low enough to make the 518 redundant.

A theory that is supported by the fact that the 518 makes other sources (AirPort, Cable) much more listenable.

For me, the 596 sound is a significant improvement vs. the 500 MkII alone or with the 518. Much purer sound.

My 2 cents. I'm ready for the flames...

John

Main system: Cable, Apple TV, HD621, G68D, AC11, 218, DSP7200SE (L+R), DSP3200 (L+R Rear)
2nd system: Cable, Apple TV, MC200, HD621, 568.2, M3100 (L+R)