I can tell you that using the 3.5mm stereo cable from either of our Sandisk Sansa's (not an iPod, but, same principle), to the 3.5mm AUX jack on my brothers Kenwood Excellon KDC-X891, results in having to turn the Sansa basically
all the way up to get enough signal to the -X891 to make the music sound OK.
Having a direct connect method like USB is
far more preferable than the 3.5mm method.
I know you mean this (direct connect method) as you said you wanted to be able to directly control it.
SonicElectronix.com is a good store to buy from...great prices, great rep. You can use
Crutchfield.com though to do some research.
Also, be aware that if your car has an internal amp (on a 'Vette, this would not surprise me in the least), you may very well have to bypass it...so the install might not be so drop in.
The
Eclipse CD5030 might be what you're looking for. Checking out Pioneer's sit though, and using the car configurator, it looks like you have either a standard or BOSE option in your 'Vette. I'm sure the BOSE would use an amp (althoguh, with BOSE, WhoTF knows), that means you're back into amp bypassing.
You might want to do some research on Corvette boards first and find a.) if you have a built-in amp, and b.) if you have a, what your options are.
It'd suck to put in a new deck and have it be less loud and/or clear than the one you just took out.
Chuck