I own both the Zen Mini with Power supply and Phoenix USB, and the Zenith MK 3 (without the Phoenix USB). As they are 2 different systems, I didn't bother to make the comparisons, as I get tired of moving equipment and cables around.
What I can say is the Phoenix USB did make a noticeable difference in sound quality, for the better. I really should move it to the Zenith and see if it does the same.
Considering the sizable price increase between the Zenith and Statement, and the fact that some reviewers find it not a significant upgrade, would give me pause.
In fact, I ended up moving up the DAC chain and got a Brinkmann Nyquist II to replace the Ayre QB-9 Twenty. It was quite significant upgrade in sound reproduction.
I have no doubt that Innuos believes it's Statement is as good as they believe it to be. But, the amount that it will 'improve' your system is dependent upon you are using, as well as how good your hearing is.
Bob