As far as I know the
EV ELX112is passive!!!
That means it is only a speaker! No mixer inside and (more important) no poweramp! So you need at least a poweramp between the KPA and your EV ELX112. If you want a FRFR where you can easily plug and play your Kemp you should get an
active speaker.
Generally I totally agree that a fullrange speaker (or "FRFR" look
>> here >> ) is the better way to go. Many reasons have already been told here (more choices in for speaker sounds in your rigs, better control over what is in the FOH (and recording), avoiding mistakes in microphone positions in a fast soundcheck, possibility to have the sound of hard driven speakers at any volume ...) I would like to add this one: all guitar speakers have quite extreme beams. That is when you look right into their face they sound really harsh and from the side they sound way too muddy. There is only a small spot (like 45°) in between where the sound is as you want it. This beam effect is much weaker on FRFR.