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
You do need to use caution inserting active devices with gain into a Quad system. Rated power can happen at .5 v input.
So for an analog solution get din to RCA w splitter and put the analog hipass before the main speaker amp. No EQ but you stay 100% analog.

relatively inexpensive and not complex after initial setup.

must know input impedence of main power amp to calculate/set xover frequency.

best

jim
Which Quad preamp ? Can rummage thru my box of toys, I know I have the AQ splitters in Seattle, would loan ya but I am not dying to do so... ha
perkri OP
I suspect, that the RCA Y-Splitter will cause an impedance imbalance
At 300ohms output impedance the Quad 33 should be good to go

perkri OP
And I would need a DIN plug to 2 RCA’s - Pre is a Quad 33 :)
Plenty of these around on ebay.
https://www.ebay.com/itm/AUDIOPHILE-4-PIN-DIN-PLUG-TO-2x-RCA-PHONO-PLUGS-CABLE-QUAD-33-44-303-405-1M/120570590087?epid=2229645602&hash=item1c12913387:g:gE4AAOxyyF5RQNWY

Cheers George