I believe that I heard that JL has new subs with higher input impedance to address this issue.Good point, but looking at the JL website it appears to apply to the Fathom v2 series (those models having unbalanced input impedances of 50K, although their balanced input impedances are only 10K), but does not apply to the E-Sub series the OP is considering. And the Fathom models cost considerably more than the E-Sub models.
In the event that I decide to add a active subwoofer crossover, I assume it will essentially act like a SS buffer right? Since both crossover has high input impedance (50K / 100K) and really low output impedance (100 ohms / 150ohms).Yes.
Good luck. Regards,
-- Al