I2S Output

Please forgive the ‘newbie’ question…but…

I started playing with my Pi2 yesterday and was very pleased with the Volumio app for streaming audio. I tried a few of the various free apps and found that Volumio was by far the easiest and most reliable.

I would like to design my own DAC board using I2S data from the Pi2. I turned on the ‘Generic’ I2S output in SETTINGS. But looking with my scope, I get no I2S data (or any activity anywhere) on any pins. A few are at 3v but most are at 0v.

I’m using the latest build 1.55.

So, what is the trick to outputting I2S data’? I gather the specific DAC settings are looking for EEPROM data on the I2C buss so they will definitely fail. Does 'Generic 'just output I2S regardless?