soundboy, i had the same thought like you too before. (as you already read my thread, hehe...)
as you know, decent cd players nowadays they dont come with headphone jack.
i dont know about shanling one, but all i know is, they are wayyy out of my budget...
the closest answer i can give you is,
i tried MARANTZ 5400's headphone jack, and i wasnt impressed at all, not a single bit.
my humble discman can outperform that marantz headphone jack anytime of the day.
strangely, when i tried my cans with the headphone jack from Denon M31 micro system, it sounded quite good... but the problem is, that M31 is a micro system, the sound is not comparable to separate decent cd player.
but i have come to conclusion that i am not going to look for a decent cd player with great headphone jack.
im afraid i have to say that its probably non existent, since the headphone jack is only sort of "another feature" that the company throw in for you.
they wont really concentrate on that department, since basically people with good cd player will have a good amp to go with it anyway..
you might be able to find a good CDP with good headphone jack in some real high end system, i dont know.
but my personal suggestion (this is probably my next upgrade)
NAD 521BEE + NAD 320BEE combo
should sound decent enough i reckon. (both speaker wise and headphone wise)