Audio can be heard from the vehicle's speakers by connecting a commerciallyavailable portable audio unit to the auxiliary jack.
A commercially-available, non-impedance (3.5 ) stereo mini plug cable is required. Contact an Authorized Mazda Dealer for details.
In addition, audio can be played from the vehicle audio device by connecting a USB device to the USB port.
NOTE
The SD card slot is for the navigation system. For vehicles with the navigation system, the SD card (Mazda genuine) with stored map data is inserted into the SD card slot and used.

WARNING
Do not adjust the portable audio unit or a similar product while driving the vehicle:
Adjusting the portable audio unit or a similar product while driving the vehicle is dangerous as it could distract your attention from the vehicle operation which could lead to a serious accident. Always adjust the portable audio unit or a similar product while the vehicle is stopped.
CAUTION
Depending on the portable audio device, noise may occur when the device is connected to the vehicle accessory socket. (If noise occurs, do not use the accessory socket.)
NOTE
Seek Switch
How to connect USB port/Auxiliary jackMazda 6 Owners Manual: Steps for Determining the Correct Load Limit
Steps for Determining Correct Load Limit-
1. Locate the statement “The combined weight of occupants and cargo should never
exceed XXX kg or XXX lbs.” on your vehicle's placard.
2. Determine the combined weight of the driver and passengers that will be riding
in your vehicle.
3. Subtract t ...
Mazda 6 Owners Manual: Front door speaker removal/installation
1. Disconnect the negative battery cable.
2. Remove the front door trim.
3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.
Front Door Speaker Installation Note
Attach the speaker with the wiring harness placed in the groove of the door
unit panel.
...