ST-M25 moving coil transformer is designed exclusively for the SPU Mono CG 25 DI MkII and SPU Mono CG 65 Di MkII.
The voltage output of these cartridges is too low to connect to the MM -INPUT terminal of amplifiers or phono-equalizers, resulting in inadequate sound volume. ST-M25 is specially designed to increase the voltage by 12dB to match the MM input of ordinary amplifiers or phone equalizers.
These cartridges supply the same monaural sound from both L/R channels, therefore L/R channels of the cartridges should be connected through ST-M25 and amplifier to the final output “speakers (L/R) ". You can enjoy the robust sound of monaural sound coming from L/R speakers.