I wonder if you could not make up a simple cable which adds the two channels together and gives you the effect of a mono switch? If your tonearm uses a detachable interconnect you could make one up (or have one made) and get the effect of a mono switch at the front end? A simple test of this would be to make up one using a male y-connector plugged into a female y-connector to check it works before springing for an expensive cable? I see Mike Lavigne suggested the same in the prior thread and I am sure this will work and is likely the optimal solution if you use a premium cable
I will observe that the hum, at least in my setup, is annoying between tracks but is not something I notice too much when music is playing but it definitely seems better to not have it at all