| posts: 5,556 | Location: Southfield,MI
The ZxR looks to be a Titanium HD replacement since it audiophile components on it as well replaceable op-amps.This time around a in-graded headphone amp. As well 5.1 analog and includes the addon board. So thats where the addon board went to, that was suppose to come out for the titanium HD. But never did.
While the Zx doesn't have replaceable op-amps but a in-graded amp still.