Ok, here is the reason for why I wanted this.
As you can see in this picture, Toyota did something really stupid by splitting half the radio controls into an upper panel. When you replace the OEM double DIN deck with an aftermarket deck, all the controls are useless. There is no reason to keep it around. Also as stated previously, I think modern decks looks ugly.
So here is what I chose to start with.
I bought this $12 stereo amplifier from Deal Extremehttp://dx.com/p/100w-hi-fi-stereo-amplifier-for-car-motorcycle-color-assorted-34408
It's claimed to be 100 watts. Whether that is true or not, I don't know and don't know how to test. I am pretty sure the factory speakers are far less than what this is claimed to be.
I then grabbed a $10 Scosche adapter:
And hooked it up.
I just tied both left channels together, and both right channels together.
This was about a month ago, and it has been working really well for an investment of roughly $25.
I am actually going to take it back apart, and build it into the OEM upper panel. I'd like to reuse the stock volume control knob, and install the fade/balance/bass/treble knobs from the stock deck into the upper panel.
For me, its a good start. Once I integrate the electronics into the existing OEM controls, it will be exactly what I was looking for, a half DIN sized amplifier with no wasted control space.
Although this is a wired setup right now, I want to get a bluetooth headphone that I can teardown, and wire into the audio input. I've been seeing this type of mod a lot on the front page, so I feel better about trying it out.