Active line level crossover with subwoofer out - HELP


Hi.

Helping my friend with another challenge. 
Looking for a line level crossover. His preamp does not have a subwoofer out.

What he wants to do is have a high pass filter between the preamp and his power amp. This so his Spendor BC1’s are spared anything below 40 or 50hz. And, the crossover needs a low pass filter to spare the subwoofer the high frequencies. 
Thoughts? 
Thanks!
perkri
Post removed 
Thanks again all! I suspect, that the RCA Y-Splitter will cause an impedance imbalance, yes? 

And I would need a DIN plug to 2 RCA's - Pre is a Quad 33 :)

I just feel this will cause some more issues.


About $100 to find out - you can order a decent quality custom quad DIN to rca cable from amazon.

does he have a Quad power amp also ???