2005 Mazda3 stock audio unit sound quality problems
 

Hi,

I have a 2005 Mazda3s with a completely stock audio system -- just the stock HU, CD player and standard speakers, no satellite/MD/CD changer, no aftermarket modifications.

A few days ago, I started having a weird problem with the sound quality becoming distorted in the bass range. Midrange and high notes sound fine, but if there's a section of music that's particularly bass-heavy, the sound becomes muddy. It's like radio interference, but only over a particular frequency range. This seems to happen with both the CD player and radio, even at fairly low volumes (6-9). I don't usually turn the volume higher than 10-11.

I don't believe it's a ground-loop noise -- it's not a crackle or hum -- and after playing with the balance controls, it doesn't appear to be specific to any one speaker.

Any ideas what might cause this? I don't know a whole lot about audio systems. I had been hoping to install an aftermarket plug-in to let me run my MP3 player through the head unit (the 2005 doesn't have an aux jack), but I'm now afraid to do so until this is resolved because it will probably do the same thing with the MP3 player.

Also, if anybody has any recommendations for car audio people in the Los Angeles area, they'd be greatly appreciated.

Thanks!

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