I was at the sony store at the mall last weekend and tried all four, xba-1 2 3 and 4.
Let me just say this is the first time in a while i've been floored by a sony product. I gotta say that the XBA-3 is probably the best of the bunch, to my ears at least. It's amazing how smooth they sounded while being so balanced. I swear, if i had the money on me at the time, i would probably have payed full retail. the XBA-4 had slightly more detail and separation, but was indeed sibilant. I really think at the price/performance the xba-3 is the peak.
I liked the xba-1 and 2 as well, and they all have the same signature which i thoroughly enjoyed. Forward mids and full bass while still being open and detailed. Best, most controlled and fullest bass i've ever heard out of a BA, and probably any other IEM i've tried to date. Full while still entirely appropriate with the right amount of impact (without being painful to my sensitive ears).
Right now it seems the XBA-1 is $80, 2 is $200, and 3 is $280.
I must agree though, that at the price point the XBA-2 may have a hard time competing with the many other options in the sub-$200 area.
I listened to 2 the least, but i'd say that if the 1 drops to $50 it would be a strong contender. If the 3 should somehow go to $200-225 I'd probably buy them. At the current price however, i'm still not sure whether the XBA-3/4 are worth it, granted i would probably say the same thing when faced with the other top-tier IEMs like W4s. They were fantastic, but still $280/350 is a lot of money.
Not entirely sure whether it's the new-sound or whether they were actually that good, but i really did enjoy them thoroughly.
Oh and the fit was fantastic as well. I guess I know where I'll be next time i'm dragged to the mall.
edit: apparently the xba-3 can be had for $190-ish... Interesting. Probably time to start saving up the pennies!
Edited by dnullify - 5/15/12 at 10:18am