Viva Fono ~$6k from Europe (60 dB gain may not be enough in my system)An important point to keep in mind is that phono stage noise levels don't always correlate well with the gains they provide.
Assuming the Underwood mods that were performed on your Jolida Envoy preamp did not change the gain of its line stage from the stock values, one of its two outputs provides a line stage gain of 20 db (with the volume control at max). A phono stage gain of 60 db will raise the 0.24 mv rated output of the ZYX cartridge to 0.24 volts, and a 20 db line stage gain will raise that to 2.4 volts. And the peak levels on some recordings will exceed the standard test conditions under which that 0.24 mv is measured by a factor of several times, which would increase the 2.4 volts correspondingly. And your power amp is specified as being driven to full power by an input of only 0.75 volts.
So 60 db of phono stage gain will be suitable relative to the gain and sensitivity structure of your system, PROVIDED that the noise performance of the phono stage is adequate. Which may or may not be the case EVEN IF the gain of a particular phono stage were significantly higher.
I'll mention also, however, that I would not draw any conclusions at all from signal-to-noise specs that may be published for particular phono stages, which tend to be defined inconsistently among various manufacturers, or not defined at all. Experiences individuals may report using specific phono stages with cartridges providing similar output levels can be expected to be much more useful.
Regards,
-- Al