i have the sp5b's
and i like em a lot. they're very crisp and quite accurate and have no mud at all. the problem is that there's not nearly enough thump in the bass....but what can you expect with 5in cones? these are great for the acoustic music i've been doing--once i got used to them, they seemed to translate pretty well to other systems.
there are two absolutely "most important" pieces to
the sp5b's, though. the first one is placement. you have to get these monitors placed exactly right.....the sweet-spot is pretty small. you'll be staying in that sweetspot for hours on end, so make sure that they're setup properly (and comfortably) in the first place.
the second is that you need to be aware of what you're NOT hearing (as much as what you ARE hearing). as i said before, bass is there--it's well-defined and clear, but there's none of that deep low end crushing thump that you'll find on larger monitors. you may find yourself overcompensating and having extremely bass-heavy mixes as a result. once you learn how to mix for what's not there, your mixes will improve dramatically. it's sorta like learning to eq by reduction instead of addition.
work with em for a while, you'll prolly like em. i really dig the mid range and highs on these monitors. that said, i must admit that i'll prolly be picking up a set of NS10's or YSM1's at some point just so i have a secondary reference that's a little "bigger" sounding. it's the natural evolution of things.
wade