New Amp or New Head Unit???

[GTCOMA]

I just replaced all the speakers in my tacoma with Polk DB650's and DB690's along with some actual tweeters in place of the paper cone tweets.

I am debating if I should get a new head unit or just a new amp to power the new speakers.

The head unit would be easier, but a little more expensive.
Head unit approx $250
Wire harness $20
Dash kit $40
Total $310

Amp option
Amp $150
Line in/out converter for factory head unit $40
Misc Wire $20
Total $210

Has anybody here ever just added an amp to a factory radio? Will it sound OK or will a new head unit add to the fine tuning of the sound? How much of a pain is it to identify the correct speaker wires from the factory harness?

Thanks for any input.

Here are a few pics of what I have done so far

[touringcamry]

I would get a good amp to drive those speakers rather than a new HU. Look in the ultimate sticky in the audio forum. It has all the wire colors and they are fairly easy to distinguish.

Maybe get something like this:
http://www.cardomain.com/item/JBLGTO754II

[schn0354]

Adding a new head unit will not improve the sound quality very much with your current setup. You are lacking power. Get a good amplifier to power your speakers. Also. I would not run two sets of tweeters in the doors. High frequencies will be over emphasized and imaging will be off. Disconnect the tweeter on the door coax speaker. Continue to use the crossover for Polk tweeter. Car doors make terrible speaker enclosures. If you dampen the sheet metal with Dynamat Extreme, it will improve the sound quality and lower road noise. Sealing up the door panel will also give you better bass response.