I have a Zenith mk3 and I agree the build is not what I’d like. It looks nice enough from a distance though. And the sound is so good that I don’t mind the build so much.
A few months ago I started experimenting with digital to digital converters, to convert USB to AES/EBU. I find that at least with my particular DAC (ModWright Elyse) the AES/EBU input notably much better than USB. Tried a few DDCs and ended up with a Weiss INT204 that I love.
I am using Veritas Cables Praesto for power and a Veritas Nexum A for AES/EBU, along with their Connexa for ethernet. I intend to add their Audax USB when it is back in stock. At the moment I'm just using an older Wireworld USB that is probably a bottleneck. It seems like the Zenith mk3 responds well to cable upgrades so I'm happy with the results.