the cartridge output is high, 5.5mv.
the pre has 48db gain for MM
are you using XLR or RCA? Some XLR outputs are stronger than the RCA output, perhaps the RCA output would tame it some.
Connections and Cartridge Loading
The JC 3+ is a dual mono design with unbalanced inputs and outputs using Vampire RCA jacks, plus balanced outputs using Neutrik XLR jacks. A custom-made three-position input impedance switch provides for 47 k ohm MM cartridges, 100 ohm MC cartridges, and 47 k ohm MC. The latter is an ideal load for some MC cartridges and high-end moving iron cartridges."