Jim, before finalizing your choice you should check to see if the specs provided by the manufacturers of the cartridges which make it onto your short list include a recommended range of load capacitance. Your Sphinx has a specified input capacitance for its phono input of 150 pf, which is highish. Assuming that the turntable cable is around 5 feet or so in length, as a rough ballpark guess I would figure an additional 150 to 250 pf for the capacitances of the cable and the tonearm wiring. That adds up to a total of 300 to 400 pf, which I know to be too high to be an optimal match with at least one or two of the cartridges which have been suggested. And I wouldn't be surprised if 300 to 400 pf turned out to be too low for some others.
And I would proceed with caution if the specs on a cartridge you may consider do not include a recommended load capacitance range. The consequences of a severe enough mismatch, btw, would be tonal imbalances in the treble region.
Also, ideally you would want to check that the weight and the compliance of any cartridge you consider are in the same rough ballpark as the corresponding figures for the Rega Elys2 cartridge, which is commonly supplied with the P3-24. Unfortunately, though, those figures don't appear to be specified or available for the Elys2. Perhaps one of the others can suggest some guidelines for assuring that you don't go wrong in those respects.
Good luck. Regards,
-- Al
