6 years loving my Zu Definition 1.5s, but it did not take much, after listening to other Zu owner experiences with their new Definition IVs. Only took me two weeks to order them, and two months for them to be sitting in my living room. The jump from 1.5 to IV is overwhelming. Two different speakers. This may just be the speaker to take me out...having fun re--listening to my tunes. Having fun