I'm sure you've already looked in this section of the forum and have found many posts about hiss with low-output cartridges. It seems to affect some people/systems and not others. A popular, though not inexpensive, solution is to use a step-up transformer.
As far as I recall there are very few reports of problems with higher-output cartridges. For example my cartridge (a Wilson Benesch Ply) is configured for a maximum output level of 1.6 mV, lower than your Zephyr, and I have no problems at all with hum.
From what you describe I'd suspect that there's something not quite right about the earth/grounding set-up in your system; perhaps an earth loop. Have you tried checking whether there's any difference depending on whether or not the cartridge is grounded to the Devialet using a ground lead connected to the fiddly knurled binding post between the two RCA phono connectors?
As far as I recall there are very few reports of problems with higher-output cartridges. For example my cartridge (a Wilson Benesch Ply) is configured for a maximum output level of 1.6 mV, lower than your Zephyr, and I have no problems at all with hum.
From what you describe I'd suspect that there's something not quite right about the earth/grounding set-up in your system; perhaps an earth loop. Have you tried checking whether there's any difference depending on whether or not the cartridge is grounded to the Devialet using a ground lead connected to the fiddly knurled binding post between the two RCA phono connectors?
Roon (Mac Mini), Wilson Benesch Full Circle, Expert 1000 Pro CI, Kaiser Chiara
Warwickshire, UK