I am looking for sound quality.

Max budget: Around $300

I plan to put these CDT's into my front doors and to run them off of the amp. The rear speakers I will keep stock and use them as fill and run them off the HU which is a Sony DSXS310BTX Digital Media Receiver. (This receiver delivers 52 watts of peak power to all four speakers while DSO and EQ3 stage 2 lets you adjust the mix for a dynamic sound experience.)

Here are the speaker specs...
CDT Audio HD-61A True 6.5″ 2-Way Component System
1 pair HD-E6 (improved for 2012) 6.5″ mid woofer
1 pair EX-530 24 dB/octave 2-way crossover, 3 dB Tweeter Adjustment
1 pair HD-100 1″ silk tweeter
Power handling: 170 watt RMS @ HPF 120 Hz
Frequency response: 65 Hz 20,000 Hz
Impedance: 4 Ohm
Sensitivity: 91.6 dB
Mounting depth: 2.74
Flush and surface tweeter housings

Also, what gauge wire should I use for the amp & speakers off the HU?