My SE output is almost burned-in. About 25 hrs to go, using it while I sleep has sped up the process lol.
Suffice to say: I'm very content with the sound. There's a big leap, I'd almost say 'giant' leap between the initial hrs and the last hrs before burn-in. Main difference is clarity, especially in the higher regions (and vocals more to the front). For bassheads however, the more relaxed bass will prove a disappointment, but it is more natural this way. it hasn't lost any precision whatsoever, just a more 'musical' bass if that makes sense.
With IEM's the SE-output leaves nothing to be desired. However, for full-canned headphones the balanced connection is perhaps the logical step.
side note: after new year, when I've got more money to spare I'll buy the Shure SRH1540 headphones (indoor usage). Anyone used it with the balanced port? And what to think of the standard Sony balanced cable, will it fit these Shure cans?