Just got my V20. How come Hi-Fi quad dac is greyed out?

Do you have headphones plugged in? Gotta have headphones in order to take advantage of it.
 
DAC Stands for Digital-to-Analog Converter. This simply means that it needs to go from the digital form, which is anything MP3 or Bluetooth style into something that is physical. If you go from the phone to anything wirelessly it is transfered digitally and then the other system deals with making it into something analog (think real). Once you go beyond the V20, the DAC isn't considered.

Back to plugging your device into your car input!