Is USB necessary for getting higher fidelity audio into the sound system?

the concept is that when you are playing music in your mp3 player, the files are all in digital format. To play audio, the mp3 player has to convert that digital signal into an audio signal to output it through your headphone jack. Then this analog signal goes into your Head Unit.

Usually during any type of analog-digtal conversion process, you are losing some fidelity. Is it enough to notice? Who knows, depends on how good your speakers are. But that's the general rule of thumb. That's also why picture and sound quality is better using an HDMI cable versus a component cable & coaxial audio cable. The HDMI cable retains the digital signal. Component cables use analog signals, which degrade as they travel through the wires.

 

However, the USB data stream is also converted to analog. The conversion takes place inside your head unit. Which is better? It depends on whether your mp3 player has a better A to D than the head unit, and also on the noise characteristics of AUX In.

Don't forget that we are talking about mp3. If you are seriously worried about music quality you are probably going to use a better format, but given that you are listening in a car, the differences are not going to be meaningful.

Tom

 

Given the fact than an automobile is a very harsh acoustical environment, coupled with the fact that the Prius interior is noisier than average, and that you're listening to compressed music files, I seriously doubt you'll be able to hear any significant difference between using the aux input or the USB connector.

If you have both, go ahead and use the USB. If you only have the aux, paying several hundred dollars to have the USB connector installed is not money well spent in my view.

If you're using an iPod or iPhone, using a dock connector to mini stereo plug cable (vs. using the headphone jack) provides higher quality sound.

 

i think the digital-analog processor in a HU will be more powerful than the one in an iPod/iPhone. Im betting the digital processors in those aren't as powerful in order to preserve battery life and are designed for headphone use only, where you dont need high fidelity.

And yes we all know MP3 quality sucks. I personally use the AAC (m4a) format, but WMA is just as good.

 

Is mp3 really that bad tho? I figure you can encode them at pretty high k and get good quality

 

Would you have link for where one could get one

 

It's not all that bad at higher rates, especially with older ears or a non-ideal listening environment.

Tom

 

On a previous car I used a Monster iCarCharger, which used the iPod dock connector, had a jack to connect a 3.5mm stereo cable, and also charged the iPod. I got it at Best Buy.

If you Google "ipod dock connector to 3.5mm stereo cable" you'll find lots of options:
[ame="http://www.google.com/search?hl=en&rlz=1B3GGGL_en___US363&q=ipod+dock+connector+to+3.5mm+stereo+cable&btnG=Search&aq=f&aqi=&aql=&oq=&gs_rfai="]ipod dock connector to 3.5mm stereo cable - Google Search[/ame]

It's best to use a shielded cable, since it will insulate against noise from electrical interference.

 

It all depends on the player. Your player or head unit must decode it before
play. If you are using the line out off the big connector of an ipod, it is likely better than either the toyota head unit or connecting through the head phone jack.

 

remember if you use the usb port it will charge your iPod/iPhone as well and you should be able to control it (track up/down etc). no such luck with a single aux port.

 

I believe the single biggest advantage to using the USB port, from a sound quality standpoint, is that the USB digital signal is nearly immune to electrical noise. Using the AUX port relies on a low-level analog signal, usually going through rather cheap and often unshielded cable, which can pick up electrical noise from a number of sources (remember, you're driving a hybrid...;-) that electrical noise is then amplified in the head unit (or separate amp) and results in hiss, hum, or other artifacts.

I have yet to hear an analog (aux) input in a car perform better than a digital signal into the head unit (through USB or other ipod interface), where it is converted to analog in a shielded environment and then amplified.

And yes, using mp3 files that were sampled at a high enough rate is important. 128kbps is CD-quality, which is usually fine in the relatively noisy environment of a car. (Audio purists may disagree, but many probably also prefer vinyl records...)

 

1 thing i have noticed Is that the sound quality Does seem a lot better via bluetooth than by cable through the audio jack. I cannot do a realistic side by side comparison but

The 1 side Has Cds burned to an ipod using a AAC Lossless the highest Quality setting.

The other is pandora Radio on my droid X Streamed via bluetooth To the prius audio system Also using the highest Quality setting available. I don't have a clue as to The parameters of the settings but it does appear To sound better

droid X

 

Oops

 

As much as I would like track up/down to be controlled through the dash and steering wheel, the "etc" part (selecting specific track/artist, playlist selection) over USB is so abysmal, I'll be sticking with line-out from the dock port connected to AUX and controlling the iPod via the iPod.