It's a bit tricky alright. Of course, you could put an air core inductor between the amp and the speaker to compensate, but that's tricky because it risks electronic resonances. Actually, it's quite unwise to attempt this unless you've made your own equipment to be bullet-proof.
The alternative is to compensate upstream, at the preamp or the cartridge step-up transformer. The obvious thing is to increase the capacitance of the 75uS RIAA compensation, starting by say doubling capacitance. Let your taste be your guide.
