Anyone listen to Zu Audio's Definition Mk3?

You can do better then Atmasphere IMO. I mated it to my Superflys which were a more favorable 16ohm, and despite wonderful transparency and great bass they were pretty lean and analytical.

Follow Phil's suggestions and go big big bottle SET. There are great options on the used market that will be much better then the atma.

A customer's comments that seems to have some relevance:

http://www.atma-sphere.com/AboutUs#Feedback

Schw06. . . What spikes do you and other Altanta Def 4s use?

Atmasphere,
No surprise, some will love your amps and others have tried them and selected something different(preferences being what they are).I suspect most of the amplifiers mentioned so far have a legion of happy customer testimonials. Variety of choice is a good thing.
Regards,

Gsm18439,
We are all using Star Sound Technologies stands. 3 of us are using the Sistrum sp-101 and the other is using a smaller stand. A call to Robert is free and he is generous with his time...A real eye (and ear) opener for me. I have Agear to thank for the suggestion.

We have the Atma S30 on the Def2 and it is an outstanding match. Not lean at all. So David has some good thoughts on different amps that work on the Zu speakers.

Only issue we have with the S30 is it is noisy. Sending it to Atma did not heal it.