The bottom line

A direct connection via auxiliary input will yield the best sound quality because it eliminates extra manipulations of the audio signal. Bluetooth adapters run a close second because, while they do manipulate the signal by broadcasting it over the air, they do so using techniques that ensure high-quality delivery of the signal to your car stereo.

FM adapters offer lower sound quality and are open to outside interference. Cassette adapters tend toward the lowest sound quality, especially if you are using a factory stereo. Aftermarket cassette stereos offer better cassette performance because of they tend to be on the upper end of that 50-70 dB signal-to-noise ratio.

Personal experience

The numbers presented here are very general. It's certainly possible that your equipment could have a superb FM tuner, or a cassette deck with a much lower SNR, for example. Besides sound quality, you should also consider the ease of hook up and elegance of the connection. And given how noisy the car environment is, you might not hear much of a difference between any of the connection options.

In the end, it's up to you. Try at least two different options and see what sounds best in your situation. And the next time you install a new stereo, spend the extra couple of dollars to buy the patch cable to connect to that rear-mounted auxiliary input. It's worth it in the long run.

What are the options for your vehicle?

Your options for connecting your iPod to your car stereo depend on a combination of three things: The kind of vehicle, stereo, and iPod that you have. Fortunately, we can help sort it all out for you — with our Crutchfield iCarStereo^sm tool.