koontz8vb

I've tried to find an answer to this by searching the forums and looking at specs online, but I've been unsuccessful. The specs comparing the 800 to 900 HiMD units show that the 900 has a "line out" function while the 800 doesn't. Looking at the photo of the 900, there isn't a separate jack for the line out, it just shows that the headphone jack is marked "line" as well as the headphones logo. If the jack is shared, what does the line out functionality do that the phones jack doesn't? Thanks!