The transformers are wound around highest-quality permalloy 80 material, and filled with carnauba. The various controls give great adjustment of input impedance to match a wide range of MC cartridges, as well as gain. There is also the option of adding capacitance to the input, which can be useful to tame cartridges having a high frequency peak. The 'impedance' control applies secondary loading resistance and together with the other controls gives the user great control over the overall sound character.

About Input Capacitance

Most cartridges have a slight peak in the high frequency range, which can be reduced by applying an appropriate capacitance at the SUT input. Miyajima recommend that this value is best set by ear, while listening to music. When input capacitance is not necessary, set the control to 0.00μF.

Input and Output Coil Settings

Setting the input and output coils alters the effective impedance load seen by the cartridge, and the gain ratio. The input coil control should be set according to the nominal coil impedance of the cartridge, as follows:
Input Coil Cartridge Coil
80 2-5 Ω
120 5-12 Ω
180 12-30 Ω
270 30-100 Ω
The input and output coil settings are the number of turns in the primary and secondary windings, and not actual impedance. The coil values can be used easily to calculate the gain ratio, for example if you choose input coil setting of 180, and output 4000, the gain ratio is 4000/180 = 22.2 times.

You can keep the ETR-STEREO in circuit even when using a MM cartridge, in which case set both Input Coil, Output Coil and Impedance controls to 'Pass'.

https://www.miyajima-lab.com/product/etr-stereo.html