It’s most likely it will not work. Most phono preamps do not have enough voltage to drive a power amp. You will need to know the output voltage of the Project. I doubt that it is more than 1 volt!
ProJect Pre BOX S2 as preamp
I have read the reviews of this unit, however have not read much discussion on it's use as a preamp. I would appreciate hearing from those having experience using it as such. Will use it in a second system with different amplifier/speaker combinations of ~$2500 retail price. Thanks in advance for any input.