If we will look on any classic SUTs we will see impedance range stated in the manual or market near the cartridge input on the SUT. In reality a low impedance MC are very low output. When a SUT says primary 3 Ohms connection it means this SUT designed for LOW IMPEDANCE cartridge only (LOMC with 2 Ohm internal impedance for example). This type of SUT obviously can NOT be used with a LOMC cartridge with 40-70 Ohm impedance.
For a high impedance LOMC cartridges there are specially designed SUT, for example a SUT that can handle 40 Ohm or higher impedance.
There is also something in the middle, for example this Luxman SUT can handle MC cartridges with impedance from 3 to 40 Ohm.
Everything marked right on the SUT, all classic Japanese SUTs from Denon, Audio-Technica are all have that marks (to match a sut and cartridge impedance), this is very user friendly! If modern SUT manufacturers can’t give a buyer this information it’s very strange and NOT user friendly!
For a high impedance LOMC cartridges there are specially designed SUT, for example a SUT that can handle 40 Ohm or higher impedance.
There is also something in the middle, for example this Luxman SUT can handle MC cartridges with impedance from 3 to 40 Ohm.
Everything marked right on the SUT, all classic Japanese SUTs from Denon, Audio-Technica are all have that marks (to match a sut and cartridge impedance), this is very user friendly! If modern SUT manufacturers can’t give a buyer this information it’s very strange and NOT user friendly!