Warren, I have pondered that very question a number of times over the past year or so. The real problem is that my audio blood has been infected by the Lowther bug.
I recently had the opportunity to spend an entire week at my daughter and son-law's home where I became reacquainted with my Lowther based Azzolina Audio Grande Sfera's. On small scale acoustic music, Lowthers are fully capable of tricking one into thinking that a live performance is occurring in the living room. The ability of Lowthers to resolve the very finest details and to get instrument and voice timbre exactly right is something that Zu's new nano drivers simply cannot do.....in fact, the nano's are not even close. On the other hand this extremely high resolution ability is the very thing that drove me to the Definitions; Lowthers make poorly recorded music sound really bad, and in many cases, intolerable. Definitons, in contrast, sound really good on most all recordings. Currently I am tossing around the idea of a Lowther project, and will likely go that direction prior to taking the next step up the Zu chain.