I'll address your Zu question. As a Def IV owner, I'm very enthusiastic about the company's approach with high efficiency, high impedance speakers flexible enough for most any amp (why not?) but especially the SET and OTL's that so many audiogoners have expressed an interest in trying. Of course, you are more interested in the more reasonably priced offerings, still, I would encourage you to step up to one with their better tweeter. ( Owner, Sean Casey, & Co. offer great customer support too.)
The Zu has been a "keeper" in my high-turnover world.
The Zu has been a "keeper" in my high-turnover world.