For the tech savvy consumer, instead of a radio, you can have an iPad or tablet in your dash. Yes it is highly custom and there are some pros and cons but when it's done right, it's very cool. Almost any dash that can fit a standard double-din radio, can at least fit an iPad mini. There are many ways to integrate physically and electronically. Please check out our gallery of tablet installations.
Inputing a tabet into a standard aftermarket radio, the tablet is simply an auxilary source, steering wheel controls can interface with the aftermarket radio and you'll still have an FM tuner and disc drive the tablet won't provide. Physically covering the aftermarket radio recessed behind the tablet is also an option.
The second option is using an external processor to take the line level, left and right audio outputs of the tabet and convert it to a standard front, rear and subwoofer output. We have a slew of devices from Audio Control, Alpine, Helix, Rockford Fosgate, JL Audio and Mosconi that can accomplish this task. The Mosconi 6 to 8 for example will provide a remote volume control, digital time alignment, third octave (30 band per channel) equalization, plus split the signal to independent pairs of front, rear and subwoofer outputs.