The Modulus is well-known to have excessive gain, it's design dating back to the pre-CD era. Most modern pre-amps provide around 12dB. There are attenuators available for inserting between pre and power, or resistors can be installed on the inputs of your power amp to lower it's input sensitivity, I believe. I could be wrong!
The output impedance of your pre and input of your power has nothing to do with the gain, however. The old rule regarding pre-amp output impedance to power amp input resistance is a ten-fold one as a minimum: 1k output to 10k input. More is better.