Aux or usb?

[Demonhax]

So i just bougth a new sterio for my car. It has aux and usb. I heard some say usb is better then aux. Is that true? In that case why? Why do studio grade headphones and really good sound system use aux?

[Oshino Shinobu]

Audio signals are analogue. Using USB will mean that it is being converted to analogue by whatever you're plugging it into, and AUX is already an analogue signal (already converted from digital most likely), so it doesn't need converting. In a car stereo system, it really doesn't matter which one you use, as you're not going to notice a difference unless you get feedback when using AUX. 

 

Studio grade equipment will often have good DACs (digital to analogue converters) that receive a digital input (could be USB), then convert it to analogue, which can be sent over analogue interfaces, like AUX. As USB is a digital format, you cannot listen to music from it directly. Sound travels in waves, so it must use an analogue interface.