I've had bad experiences with inphase stuff in the past. Subs, amps, components lasting under 6 months. Not sounding great compared to other brands. They are a budget brand and there is better out there for the same money. Fusion, Vibe, JBL all much better than inphase mate.
Comps = component speaker.
A component speaker set is a set of different size speakers, with a crossover which sends each particuliar speaker the optimum frequencies for it to receive.
For instance. The HU (head unit) sends out 20Hz-20kHz along down the speaker cable. Now if you tried to play 20Hz through a teeny tiny tweeter it would die. It's designed to play from around, say 5kHz. The crossover stops any frequencies under this particuliar point reaching the tweeter. Instead it send them to the other speaker in the set. A midrange for instance, whic is able to play between 60Hz & 5kHz.
Co-ax is basically a comp in one unit. You'll notice it has a little tweeter on the front of it. It'll also have a built in crossover to protect the inbuilt tweeter.
Generally the bigger the speaker the lower the frequencies it prefers to play. Hence the reason subwoofers are normally a lot bigger (10-18inchs generally) than full range speakers (normally between 8 & 4inchs).
When you buy a set of comps you'll normally have 2x bigger speakers (mids), 2 tiny speakers (tweeters), 2 crossovers (little device to split frequencies between speakers).
