Yeah, the Kustom's are unpowered - you still need an amp for them. The sound is marginal (at best) from any of those low-priced Kustom PA/monitor speakers at low volume, as soon as you start to put any volume through them they are crap. And PA speakers, in general, do nto make good studio monitors due to design (sound dispersal patterns).
To JLondon's question - Not sure the Thumps would make a very good monitor, when used as a wedge - the problem being the way the sound spreads out from the horn. I've heard the low end is pretty muddy on them, but never actually heard them in action myself. Mackie has a new Thump model out, so the old ones are going cheaply now.