It is amplified. If yours is labeled like the one I have you will see two icons on the back side right above the output jacks. Both are headphone icons, one thicker or more bold than the other. This indicates they are for use with low or higher impedance headphones. The 47 ohm output is recommended for line out duties as well. I am sure that this is because it is a better match for the typically high impedance inputs of other amplifiers. This is typically 10K Ohms.
Plug a set of headphones into the 47 Ohm output, fire up some music, play with the volume control. Let me know what happens. Does it drive the phones to a similar level as the 0.47 Ohm jack? Do a quick A-B comparison. In my case it drives the HE-400 just as hard out of either, though it does sound different due to damping factor differences (especially with higher Z phones like the HD 650).
If that is not an amplified output, then I am confused about what that term means. It sounds like the definition of an amplified output to me.
Who said this you asked.
All of the people, including LH Labs, that say that the 47 Ohm jack can be used for higher Z headphones are essentially saying that it is an amplified output. You can find many reviews and even descriptions directly from LH Labs that make this statement.
Here is one:
There's on-board volume controls and little LEDs that indicate what sample rate you're currently playing and two 3.5mm analog outputs, 47 Ohm for the line out and higher impedance headphones and 0.47 Ohms for lower impedance headphones.
Or this from the GO Kickstarter page:
Problem - You want to share your music with a friend. So, you hand him or her one earbud, and you listen to the other. That sucks!
- It's a shareulator. GEEK has two headphone jacks!
Of course, an amplified headphone output can act as a psuedo line output to drive another amp, as long as it can swing the required voltage into the HiZ load, but it is still an amplified output. This means using it for this purpose is "double amping"!
If you are interested take a look at this article:
While the GO 47 Ohm output can be used to drive an amp, it is not anything even close to a true line output.
Edited by mandrake50 - 8/13/14 at 7:01pm