Cartridge Output and Phono Stage Gain
A line stage preamp needs to see about 325 millivolts (mv) from a source component. If the incoming signal is much lower, the line stage won’t produce realistic listening levels while maintaining a quiet background.
CD players, tuners, tape decks and such all produce 325mv or above, so they drive your line stage just fine. However, most phono cartridges (including all the good ones) output far less.
ZYX’s output only .24 or .48mv, literally 1/1000th the voltage of your CDP. Phono stages, head amps and step-up transformers all help boost this tiny output up to the 325mv that your line stage needs.
So the next question becomes, how much voltage gain do I need before my line stage for a particular cartridge? This question is usually answered in decibels (db). db are simply a different way of expressing voltage, db gain is a log function of voltage gain. As such, a .24mv cartridge needs 63db of gain before the line stage. A .48mv cartridge needs 57db.