I think the expectation is that analog adapters will identify as such and programs will be able to specify that they only work with playback devices (speakers,

I think the expectation is that analog adapters will identify as such and programs will be able to specify that they only work with playback devices (speakers, headphones) not analog adapters. We of course know aftermarket adapters won't care and you will always be able to hack apart headphones to extract the the analog signal. I don't think DRM is a primary goal though it's just something you include because rights holders will occasionally demand it and if you offer it you open a few content doors for your platform. It doesn't matter if it works really.