A phono stage, also called a phono pre-amp, provides the connection between the record cartridge/pickup (stylus) and the amplifier.

Turntable cartridges output a very small signal. This signal needs amplifying up to several hundred times the original size before it is loud enough for your amplifier. A phono stage increases the signal level from millivolts to volts.

When vinyl was the standard for audio recording, the phono stage was built-in to receivers and amps, allowing direct connection of a turntable. These days most receivers and amps do not contain a phono stage so a separate unit is needed.

It is a necessity for any turntable without a phono stage already built in. It will also upgrade a basic built-in phono stage in a turntable or amplifier system.