My headphone rig in its last high-end state, before I sold parts to cover closing costs on a house.
Furman surge protector > Sony XA5400ES > EAR HP4 > HD650
Best sound I've owned/heard thus far (which is admittedly rather limited in scope)
Everything sounded great on it if it was a good recording to begin with. I was especially impressed with how it handled Immolations' album Close To A World Below.
Its not my favorite album or anything like that, but it is the most dense recording I've heard, and it sound like a sloppy glob of chaos on everything else I've heard it on.
Here I could actually make out all the guitar overdubs and finally gained a deeper appreciation for the dissonance they use throughout.
I also believe better tonality was allowed to peak through. It really is a dense, fast record with no space around the instruments to breathe whatsoever.
I haven't heard this rig in well over a year, though I do still have the Sony unit which has migrated to my home theater along with the Furman.
The headphone rig previously used a Bel Canto Dac3 for ~ 2 years before switching to the Sony. I probably used the Sony with it for a year or so before selling. Hard to recall for sure.
I have no illusions that it can't be bested, I just have a limited exposure to high end equipment. Had a blast while I owned the stuff.
When I get back in the game soon I will either go speakers or stax or both.