DMax is both film contrast dependent and paper dependent. Most RA4 papers tend to be a bit anemic in this respect, at least if you're comparing them to the deep blacks of past premium color processes like Cibachrome or dye transfer. Modern inkjet color prints suffer from irregular blacks, clumsily necessitating up to three different blackish inks in the set, with, arrrgh, dissimilar sheens! Provided you are processing the prints correctly, you might need to increase the contrast of the neg either by learning contrast-increase masking or by switching to a punchier color neg film like Ektar, or via both. Down Under, where you are, Andy Cross is a teacher of various such techniques. You will also get richer blacks from Fujiflex Supergloss, which a pricey polyester rather than RC paper medium, but now available only in full rolls.