Zu Defintion 1.5 vs Def IV

I own the Zu Def 1.5s. Hurricane Sandy blew one of my speaker amps; with the many quick power surges. Got me thinking, rather than have Zu replace the amp, maybe the Def IVs are the way to go. They have gotten a bit more expensive. Any takers who have heard (owned) both, that can give me detailed specifics whether it is worth the upgrade or not. Thanks in advance.