Okay, I ran sound from my MP3 player through the Auxiliary input jack. Couple of issues:

1) I bought a cigarette lighter adapter (output is USB outlet). If I have the MP3 player plugged into the adapter (mine has rechargeable batteries) while playing music, there is a significant amount of background 'clicking'. The clicking goes up and down with the speed of the engine. Is this normal, or do I just have a bad cigarette lighter adapter? There is no clicking noise if I disconnect the MP3 player from the charger. If this is the way it is, this sucks, because I'm always playing music when driving - so to charge my player, I'm going to have to constantly bring it into my home? Or worse yet, sometimes listen to FM radio ...

2) Even with the MP3 player not connected to the adapter, the soundseems of lower quality than if I play a CD. Is that normal?

Just in case it matters, I havea Sansa Express MP3 player ... made by SanDisk, it's a good one.

 

To answer your first problem you have alternator whine. To fix it you need a ground loop isolator (Wiki "ground loops" for a detailed explanation). You can get a RCA to RCA GLI at Radio Shack for around $12, however since it's RCA you'd also need RCA to 3.5mm adapters for the audio jack on the player, and the ACI in the car. Crutchfield sells a 3.5-3.5mm GLI for about $17. Look HERE.

As to sound quality, a couple of questions. First off are you running sound out of the headphone output, or a line level output (*I just looked at the specs and didn't see a line level, so I'll assume you're going headphone)? You could try turing up the volume on the player to see if that makes a difference in sound. Another thing that could be effecting your SQ is the compression of your Mp3s. If you use really low compression Mp3s in order to fit more on your player then they're going to sound like crap plain and simple.

 

Thanks IC. For now, I don't foresee myself jerking around with all the wires. If I proceed with it, I'll have, 1) The MP3 player, 2) The cigarette lighter/USB output power source, 3) The GLI, 4) The RCA to 3.5mm adapter, and 5) the 3.5mm audio cable. That's a lot of crap considering my car is supposed to be conveniently wired for this.

As well, with the MP3 player, you havemuch lesscontrol over the music with your steering wheel or dashboard buttons (ie. no track selection ability) - all you can control is volume, off/on, and play with bass/treble.

I have my compression rate set for very high sound quality (according to Media Player 10, I use about 69MB per song). So I think the sound quality issue is just a combo of running sound out the headphone output, through audio cable, and/or through Mazda's wiring. It won't be as good as reading it direct from a CD.

It's not useless though, for a long road trip (rare for me), might be nice to have the MP3 as a way of randomly playing a couple hundred tunes without the hassle of changing the CD every 70 minutes. I can understand why people are annoyed the standard CD player cannot handle MP3 CDs.

 

Hmmm, I don't see how having a GLI, two RCA-3.5mm adapters (you need one for each end of the cable...... though the rat shack one does come with one) is easier than the crutchfield GLI with the 3.5mm cable you already have.

 

Okay, IC, I now see what you mean. I didn't read your initial post carefully enough. The crutchfield GLI would be the best answer.

And, in follow up to my earlier comment, I found that by playing with the equalizer built into my MP3 player, I was able to significantly change (improve) the sound quality. Having the volume of the MP3 atroughly75% seems to be theright settingin my situation.

 

I thought the CD would play MP3 CDs. Have you found that not to be true? Obviously, I have not tried it, or I would know.

 

The CD/Mp3 player is an accessory and doesn't come standard on any models (in the US). A couple people have negotiated the price of the Mp3 deck into their sale price, and I think occasionally a dealer puts them in by themselves to jack the price up without telling anyone.