Optical Cartridge Inputs
The number of inputs accepting signals from optical phono cartridges. A left/right RCA pair counts as one stereo input, not two. Separate MM/MC inputs, line outputs and TOSLINK digital inputs do not count.
Optical describes how the cartridge senses stylus movement. The tonearm carries an analog electrical signal, not digital audio through an optical fibre.
Optical Cartridge Inputs — Optical Equalizer
An optical equalizer supplies the supported cartridge’s operating power and applies the equalization it needs. An ordinary MM/MC input cannot replace this interface, even when the plugs fit.
More inputs let you connect more cartridge sources; they do not establish better sound. Check the equalizer manufacturer’s supported cartridge models and tonearm wiring requirements before connecting. The count alone does not establish compatibility. If the number is missing, treat it as unknown rather than zero.