M³ is a so-called transimpedance amplifier. While most phono preamplifiers treat the pickup cartridge as a voltage source, M³ uses it as a source of current. This solves all the problems of preamp's input stages interacting with cartridge's inductance and cable capacitance. It also provides for better noise performance and eliminates the electrical resonances in the audible frequency range.
Very few companies used this principle, because the frequency response of a transimpedance stage depends a lot on the source (cartridge's) inductance and resistance. While it is easy to build a custom transimpedance phono preamplifier to match a particular cartridge, it would have to be rebuilt to use a different one.
M³, however, adapts itself to the cartridge. It uses the built-in LR meter to measure inductance and resistance of the actual cartridge attached to it. Then the microcontroller does the necessary calculations, and the parameters of the transimpedance stage are adjusted using high-precision digitally controlled potentiometers. To shorten the signal path even further, M³ uses the cartridge's inductance to form one of the RIAA correction poles.