A lot of times, the RELs need to be set far below where you think the rolloff of the main speakers is "supposed" to be. In other words, if your mains go down to 40 Hz, set the sub somewhere in the upper 20's, and then play with it from there.
Having used just about every REL ST mkIII there is, and being a big fan of REL in general, I have to say that the Storm III is by far my least favorite. Compared to any of the others, even the Strata, it is exactly as you described, "muddy and abstract". This gets a little better with age, but not much. Hey, it's a bass-reflex box, comes with the territory. If there's any way you can afford it, the Stadium III is a giant leap upward, to say the least. If not, I would take a Strata anyday over a Storm. It won't go as low, but at least it sounds like music and not an indistinct thump.
Having used just about every REL ST mkIII there is, and being a big fan of REL in general, I have to say that the Storm III is by far my least favorite. Compared to any of the others, even the Strata, it is exactly as you described, "muddy and abstract". This gets a little better with age, but not much. Hey, it's a bass-reflex box, comes with the territory. If there's any way you can afford it, the Stadium III is a giant leap upward, to say the least. If not, I would take a Strata anyday over a Storm. It won't go as low, but at least it sounds like music and not an indistinct thump.