I have compared the Zen to the Zenith and there is a big difference. Unlike some manufacturers I know, you can clearly hear gradations of improvement, Zen to Zenith to Zenith SE, to Statement. In each case, you can hear the difference, in a few bars of music. I have been trying to get an audition of the Phoenix for some time, no luck with Covid around. The scuttlebutt is that the Phoenix gets the Zenith to near the Statement.
I have a Zenith Mk 2 and think it's one of my best purchases. It sounds great and ripping couldn'tbe easier, which is not true for many competitors.
If I was I was in your position, I would buy a Zenith Mk 3 now and get the Phoenix later, maybe if one comes up used.