Greetings
Thank you for the examples, but I don't understand how the DAC handler function is called, neither what name should it have, I can only hear static, the DAC is not running at all, what Am I doing wrong? Could you please take a look at my code? I'm confused. 
I'm still having the voltage swing issues, even using your example code, could you test it, and see if it also happens with your arduino?
ard_newbie:
If you want to use an external DAC, Google DAC DUE SPI and you will find a relevant .pdf from chianorobotics.
Thank you, but I've already tried that configuration, and I've those DACs, the MCP4922, but the problem is, I can't use them when I'm reading a file from the SD card unless I use a software defined SPI or UART SPI, because the SD card's CS can't go low without closing the file. Any suggestions to solve this problem, I don't know much about software SPI or UART SPI.
Wav file reader code that it's not working: DumpAudioFile5_optimized_dma.ino
Voltage swing not reaching limits on channel 1: sketch_mar08a.ino
Regards,
Daniel
DumpAudioFile5_optimized_dma.ino (22.7 KB)
sketch_mar08a.ino (2.47 KB)