those speakers really do require an amp to get them to do what they were made for. of course you could run them off the HU for a little while till you saved up some money to get an amp but they wouldn't sound much different than regular coaxial speakers if they are just getting power from the deck. also don't event think about turning them up if theya re just being run off the HU you could damage them severely.
yeah i'm gettin xr 6.5 but have no idea what amp to get. i was thinkin about a jl 300/4 but i dont think its nessesary spendin 350 dollars to power 2 speakers.