@cascadesphil
I cannot imagine modifying the filters for the CS3.7 (really, any speaker but especially first order designs) based on John Atkinson’s quasi-anechoic measurements! That’s whack.
I actually exchanged messages with that ebayer (his ebay history is spotless!) as I was buying my 2.4SEs. He had an ad for tweaking the 2.3 and 2.4 XO. I was flirting with the upgrade idea even before exchanging ideas with Tom Thiel. I am super glad I worked with Tom instead!