I have the 520c for my 590 L/R (I got the 580s too, but for surrounds, my 530s will become rear surrounds or heights...). It uses the same compression driver as the 580/590 from what I know so assume it is the better match but am also interested in anyone who's tried the 235C instead. Not so worried about the woofers, as I cross them fairly high in any case.
