However the phenomenon is not audible......I'm still not satisfied with the result.
Think about that... You can't hear it, but you're not satisfied because you have the ability to measure the noise. You're never going to get perfection. It's analog* so there is always some noise.
Imagine that you can get the noise below the level where you can measure it... Are you going to become dissatisfied again if in the future you gain the ability to measure it?
There is audible noise from the record, and perhaps some hum & hiss from the preamp. If you want to worry about something, worry about the audible limitations of analog vinyl...
If I were in his place, I would want to digitise the records with the best quality I can achieve, no matter whether I can hear the noise or not.
Sure, but I consider it useful and sensible to separate the avoidable noise from the unavoidable noise, and try to get rid of the latter.
That only makes sense if the avoidable noise is not already far less than the unavoidable noise. In this case the avoidable noise (due to the use of 44/16 ADCs) is typically far less than the unavoidab le noise in the vinyl media.
Better safe than sorry.