Which has better audio quality: bluetooth or aux in?

[IanM]

I know to some extent the aux in audio quality will depend on the player, but if you play music through a car stereo via bluetooth and via aux/line in (say from an mp3 player), which will sound better?

[tcbassist]

Even though mp3 is compressed, it is decompressed at playback.
There are those that will say that Bluetooth will sound the same as aux/line in, and under good conditions it does. Bluetooth is however wireless technology and just like anything wireless it is subject to interference from anything that operates on a simular, or close to same bandwidth. Ever used a Bluetooth headset and got static in it? The same can happen in your car, so I think Aux/Line input is the better way to go if all you want is to get the audio from your device to the stereo. It is usually the least expensive also.

[lenb]

MP3 is "compressed". The Aux. input on a receiver isn't.

[tcbassist]

Even though mp3 is compressed, it is decompressed at playback.

There are those that will say that Bluetooth will sound the same as aux/line in, and under good conditions it does. Bluetooth is however wireless technology and just like anything wireless it is subject to interference from anything that operates on a simular, or close to same bandwidth. Ever used a Bluetooth headset and got static in it? The same can happen in your car, so I think Aux/Line input is the better way to go if all you want is to get the audio from your device to the stereo. It is usually the least expensive also.