I think it's possible that you may get too much response (amplitude and possible phase issues) in the upper frequencies of the sub. You will have those freq's played through the mains & also through the sub.
That's why the subs have a cross over (the high level input goes through the crossover & is divided with whatever slope and xover point the circuit is designed for). That is how the freqs mentioned above are controlled usually. (Having said all that, I kind of do the opposite thing that you describe--I have Gallo's which drive their woofers the xover from the full range binding posts & drive the woofers directly from the secondary binding post--but there is a second crossover and amplifier in the Gallo SA).
Good luck,
That's why the subs have a cross over (the high level input goes through the crossover & is divided with whatever slope and xover point the circuit is designed for). That is how the freqs mentioned above are controlled usually. (Having said all that, I kind of do the opposite thing that you describe--I have Gallo's which drive their woofers the xover from the full range binding posts & drive the woofers directly from the secondary binding post--but there is a second crossover and amplifier in the Gallo SA).
Good luck,