I'm not really familiar with the 904 series. From what I've read about them -- they're the P.A. version of the 604. Higher power handling and better h.f. dispersion (Mantaray) in exchange for a slightly narrower bandwidth? Is that pretty much it? They seem to be a lot less common than 604's---due to being in production for many less years..... They've got tangerines and a great crossover with h.f. and mid compensation--he's asking $790 OBO so he's willing to deal---sounds like a real bargain for these if in nice shape (no pics).......

BTW, he says these are "new"--if really NIB they're a steal!