Thanks Phil. Actually, I've always found Zu products haven't required serious break-in, obviously several hours must be performed at the factory before they're delivered. This applies to the Zu Event phono cable I've bought recently: it sounded great out of the box, and has only improved a little in the intervening month of continual use.
When I bought my current Def2s in winter 2007, it was pretty cold, and it took a good month for the soundstage to widen as the drivers physically warmed to room temperature. Since I'm going to take ownership of the Def4s in the summer, temperature should be less of an issue.
Great to hear your Def4s sound so good so quickly, and continue to impress.
