Hey Lon,
Thanks for checking in.
Yes I definitely have new impressions but I am reticent to go deep with any final comparisons for a couple of reasons. I am on day 10 and the ZDAC has become notably more open and resolving over the last few days. A jump to be sure, but I expect more to come.
And....to further mess up clarity of analyses, I am still messing around with cable synergy (power and IC's and switching around my little Alan Maher boxes of rocks on the power cable ends). Also, I am waiting on a little better USB cable to more accurately compare a computer front end.
But maybe I can speak to the break in process so far!

Before this sort of transformational shift of the last two days, I was hearing progressively better sound, but there was still a lack of total resolution that sounded to me like it could be unsettled electronics. The pleasant anticipation of better things to come was supported by the fact that during those first 5 or 6 days, there were points of blissful brilliance as the sound kept subtly shifting.
But at that point, though better, I could not say for sure the ZDAC was
considerably better ($800 worth) than my Rega Apollo. They really were quite different in their presentation so it was tricky because I liked things about both. Comparatively, the Rega was more laid back, open and spacious (more black between players) but sometimes a little lean and on rare occasion, perhaps a touch electronic sounding. Ouch!.. that was a brutal blow the ZDAC dealt.
The ZDAC on the other hand, was more full and rich, with generally nicer harmonics and a little smoother. It was more forward, with a relatively equal soundstage, but for me, perhaps filling in the black a bit much, giving a live sense, but feeling a little less spacious...something I enjoy. So though pleasantly resolving, I found it a little too full and forward for my ultimate druthers.
Hypercritical listening aside, the ZDAC always sounded good, BUT NOW it is beginning to sound like I would suspect it should for Steve to call it good! Somewhere around days 6-8 I could hear a speeded up shift in the low end detail, then yesterday the upper mids and highs leaped up a step, smoothing and clarifying along with another dose of opening in the low mids and bass. But as the detail and space jumped forward in the equation, I found the mids just a little hard sounding.
And Today???....the detail increases with more smoothness and with increased harmonics rounding things out in a pleasantly musical way...Very Nice! So at this point, I'd say it is sounding really good but figure it is still sorting itself out! I am excited to hear it tomorrow!

So it is all in flux for me and the ZDAC is still burning in as far as I can tell, but I will write once I feel like it is close to finished.
How long did it take for you to consider yours burned in Lon? How about you Randy?