@wspohn Wow, cool. The model 4 are getting long in the tooth and i believe no replacement drivers available. RV still use the same basic architecture of powered bass in the sub 3 and Quattro and up floor standers…because as noted it works ! Newer models include 11 bands of EQ below 120 hz. You should join us over on the Vandy owners forum…pictures of the model 4 would be a cool hit there…
Best to you
Jim