You have the other problem, which is SS pre driving tube amp. There are a few parameters of your amp you will need to get.
a) The input impedance of the amp.
b) The gain of the amp or input sensitivity of the amp.
For a), it is almost guaranty to work because SS preamp (the Purist in this case) has very low output impedance (with respect to a typical tube preamp), and tube amp (historically) has high input impedance. This is the ideal condition because it translates into high power transfer ratio.
For b), most if not all today amplifiers design to work with 2V or lower. The Purist has 12 db has gain setting from 0 to 12 db so most likely it will be able to boost the signal from the source to drive the amp to its max power.
Either Curt or I will be able to tell you for sure once you get the input impedance and the gain specs of the amp from the manufacturer.