It is surprising how many different types of cartridges can work with the FR-64, despite its heavy effective mass. An obvious first choice would be the FR-7 series. You can get an early (silver) FR-7 for around $1000 and the improved FR-7f for around $1500. The FR-7fz and the final MC-702 variations are superior still, but have become quite rare and expensive.
But if you don't fancy hunting down such vintage systems (with all the risk that goes with that territory) I would strongly recommend the Phasemation PP-300 (or earlier P-3G), which you can buy new for around $1500. Truly a marvelous cart and a great match with the FR-64S.
But if you don't fancy hunting down such vintage systems (with all the risk that goes with that territory) I would strongly recommend the Phasemation PP-300 (or earlier P-3G), which you can buy new for around $1500. Truly a marvelous cart and a great match with the FR-64S.