I disagree entirely. I have owned both for a fairly long time now.
There is a terrible problem with the Sony's--their midrange continues to develop with use until it's too "thick." Out of the box, the 888s sound rather peaky in the treble and bass shy, but the midrange is already rich and smooth.
I performed the infamous "groove mod" so popular here many moons ago--it really gave out thumping bass, and as the treble settled the 888s sounded perfect. At that stage it was truly audiophile quality IMO. But then the bass started to develop more, and with the groove mod the bass was just bloated and overpowering, so I took off the groove caps and went back to original rubber rings. This was fine--again the sound was fairly balanced and the 888s were heaven again. But about three months ago I noticed something horrifying--the midrange was developing more and more, and not stopping(!). At this point (now), the midrange is just way over the top. It envelopes the treble and is just too damn "thick." If some of you think the Senn580s have a "veil," wait till you own a pair of 888s for 2+ years!
At this point, they're fairly unlistenable unless I couple them with an amp that accentuates the treble heavily. Sometimes I plug them into my Cosmic and turn the "brightness" setting all the way up--this works for most music. But considering that the 888s are primarily for ultra portable use, they're rather useless (unless you consider a Cosmic + battery pack "ultra portable.").
So that's my story. They were a good investment at the time, but 2+ years on they've become fairly unlistenable. If you think that's not a lot of money to spend for two years of enjoyment, go for it, but the Etys are considerably better in sound quality, and AFAIK do not get worse with age.