How are headphones used on the One?

What headphones should I use?

I'm hearing impaired. How would headphones work for me?

What about connecting the One to my wireless transmitter that I wear round my neck and has a wireless connection to my hearing aids?

What about a Bluetooth connection to my Bluetooth hearing aids?

Can you be specific about the connection between One and external devices?

What Filter settings do you recommend for connecting One to external devices?

What about other listeners? I want to allow others to listen to what i'm hearing.

How many headphone sets can be driven directly from the One?

What about using external speakers? I want to play sounds in a classroom.