You're getting some number approx 10^2*sqrt(10) which gives you approx 300 times and doing wrong nothing. So you're getting an approx output voltage of 240mV. Now you should check specs of your preamp in terms of input sencitivity which has to be bellow 240mV and moderate gain of 10...15dB. Otherwise I would pickup a high output version of the same cartridge for its maximum performance.
Happy Listening,
Mara.
Happy Listening,
Mara.