Asking for a friend . . . The Rega Elys 2 (a natural match for the P3 I think) specs out with an output voltage of 6.8 - 7.2 mV. The Naim lit for the SN3 says its phono stage is “suitable for 5mV cartridges.”
Is this an OK pairing? Or should an SN3 owner find a slightly lower output cartridge?