You are missing the forest (system) by focusing on a tree (one component). Too high or too low gain depends on the output of the cartridge + gain of phono pre + gain of pre + gain of amp + efficiency of the speakers.
I'm assuming the Xono is the new component so you are focused on it, but if the gain of some other component was lower you would be OK. Before adding a component you should do the calculations to see whether or not it will give you too much overall gain.
BTW by "too much gain" I assume you mean you can't turn the volume up very far before it gets too loud; and yes, that does compromise the overall performance.
I'm assuming the Xono is the new component so you are focused on it, but if the gain of some other component was lower you would be OK. Before adding a component you should do the calculations to see whether or not it will give you too much overall gain.
BTW by "too much gain" I assume you mean you can't turn the volume up very far before it gets too loud; and yes, that does compromise the overall performance.