It delivers CD-quality sound directly into the factory sound system via the CD changer port, without the loss of sound quality that occurs with existing cassette and FM transmitter solutions.
Audi ISO 8Pin USB+SD MP3 Adapter

Directly control from car stereo panel, user only need a SD card or USB disk, then you enjoy the digital music (MP3/WMA) in your car, Aux input for external audio sources, Auxiliary devices such as MP3 players, Potable DVD players, MiniDisk Player, handheld gaming systems, notebook computers and IPHONE can be added to the OEM radio while delivering optimum sound quality.
 
 
Features:
1. Plug&play, CDC alternative
2. Connected with wire harness, not FM signal controlled ,Hi-Fi guaranteed
3. Controlled by vehicle Head Unit, support Steering wheel operation
4. With imported Hi-Fi Decoding Chip, perfectly support MP3 and WMA tracks
5. Supports SD/SDHC/MMC card/U Disk/Card Reader/Hard Disk
6. Supports external audio source(MP3 MP4 PSP Mobile Phone) via AUX in port
7. Playlist function same as multi CDs
8. Supports Last Position Memory (LPM)
9. Vibration and interference proof
10. Easy to install, no damage to original car decorations for different car models or car radios
Compatible with:
 
Audi:
1999-2005 A2,
2001-2006 A3,
1998-2006 A4/S4,
2001-2004 A6/S6,
1999-2003 A8/S8,
2000-2005 AllRoad,
1999-2003 TT
  Note 1: 
(1) Compatible with the following factory radios:Audi: Chorus 2, Concert 1, Concert 2, Symphony 1, Symphony 2, (2) Not compatible with Navigation system
(2)Audi 20pin connector  is optional for avoiding modification on Audi 8pin radios
 Audi 20Pin connector:
 
 
 
Available Solutions:
For OEM radios : VW, Audi, Toyota, Honda, Mazda, BMW, Hyundai, Kia, Acura, Lexus, Skoda Citroen, Fiat, Volvo, Mercedes, Nissan, Suzuki, Ford, Renault etc
For after market radios: Clarion ,Alpine, Blaupunkt, Sony, Sanyo, Panasonic, Pioneer, Becker, JVC etc
installation Guide:
 
 
1: Pull out the unit from the car and touch the back of the unit for CDC port when the ignition is switched of.
2: Insert the CDC plug into the original car port correspondingly. Then insert the storage card.
3: Then check if the device works normally or not after power supply given from the car itself.
4: Put the wire harness into the proper and good place after the test successfully.
 

Packge including:
 1. Digital CD Changer
2. OEM compatible harness to connect to the back of the car stereo
3. 3.5 mm Male / Male Audio cable
4. Installation manual