Almost all High Output MC Cartridges have a 47K impedanceNot sure that this is correct?
It is certainly the default impedance of many MM cartridges but most MCs, especially LOMCs in my experience, are far happier at impedencas from 100-1000 Ohms?
In fact my Halcro DM-10 preamp phonostage fixes the MC impedance input at 220 Ohms whilst allowing adjustable impedances for MMs from 10K to 60K Ohms.