This cartridge looks to be a modern version of the Signature Series of cartridges from the mid-80's that included the MCZ, XTZ and TLZ. Those were all "designed" to work at 47k though in some systems they sound better in the mid 20's. The best you can do is experiment from about 23k to 47k and see what sounds best to him. I would think that somewhere between 45 and 50db gain would be about right.