Dear @drbond : You already know that in the audio world always exist trade-offs when we want to make some room/system changes, nothing is perfect so don’t try to look for because just does not exist.
You need only a high pass because the low pass is made it by the sub’s. Now you can have that high pass with and active external crossover or you can do it at the input of your amps and for me this is the best high-pass trade-off because you add almost nothing: no added electronics, cables and input/output connectors.
The signal that goes to the amps from the CH goes directly or through the external high-pass filter and from your CH goes too directly to the subs. Btw, usually the high-pass filter setting up is in the 80hz-100 hz and you do not needs that the external/internal high-pass has additional gain because the high-pass gain is handled by the preamp. The gain of the low-pass by the sub's.
That’s it.
R.
@lewm : " I truly did wonder why you thought Raul’s quote was humorous. " . Easy, because he did not think in that way before. Seems to me that is his way of audio life kind of think because he posted twice something with no sense in reference to what I posted about sub’s, he said twice: " you was not the first person to said that " .
But where in hell posted I that " I was the first audiophile to said that " ?