Cartridge incompatibility, Soundsmith and Luxman

I have a Soundsmith Zephyr MIMC Star cartridge that sound really amazing, but I just changed to a Luxman L-590AXII and the gain and loading is fixed.

Output/loading for cartridge: 0.4mV, recommended load resistance 470 ohm

Input sensitivity/impedence for the amp: 0.3mV, 100 ohm

The gain should be ok, but the load is way off and you can clearly hear it. The highs are rolled off and I need to crank up the volume to be acceptable level.

So here's the question... what cartridge would work in this setup? Would love to keep the Soundsmith, but I'm not going to add SUT with additional cables and all that complexity.