Hold my beer and watch me solder this. I can appreciate upgrading a mid-fi speaker and you really can derive palpable benefits from minimal investment. ATC does their homework and produces a world-class product. I question improving their design work.
I’m biased as I’ve a pair of ATC 40As and a pair of ATC 50As. The 50As courtesy Lone Mountain. Best of luck finding the right pair to do surgery on. I’ve Frankensteined a dozen pair over the years.