PA gear has the potential to sound lovely, though there are some problems, generally with getting a dead enclosure and getting a nice top end.
I firmly disagree that you need an XTA controller for PA kit to sound respectable. For serious DIY I cannot see how passive crossovers have much of a place left with the DCXs and affordable measurement kit as cheap as it is at the moment.
Current system: 1" compression driver on RCF H100 clone crossed 1.5kHz acoustically to a P.Audio Winner 12S in tops cabs and at 110Hz to P.Audio C18-650EL is very solid Bass-Reflex enclosures tuned to 40Hz (or 25 when needed)
I have A-Bd some Behringer passive Truth 8"/1" monitors (which went astoundingly flat except for a slight 1.5dB peak at 2.5khz and a 2.5dB peak on axis up top which doesnt' really go away off axis due to the waveguide diffraction) both eq'd flat (like +/- 1dB from 500hz and up, thank you kX drivers) and the dynamics the pro-sound kit gives you is just absolutely addictive. Most hi-fi kit doesn't quite do it anymore on large orchestral works or rock (none of the hyper compressed shank so often heard these days) after getting used to prosound drivers.
BTW, anybody wanting a really nice cheap pair of "hi-fi" speakers who doesn't mind a slightly bright top end (but all withing less than +/- 2dB in the mids and above) should have a look at these first imo. Solid cabinett and for less than one could build them. Surprizingly clean waterfalls too. Only add-on would be a Grille cause they look a little different, but that's about it.
Martin