Can this be used as a headphone amp?
http://runoffgroove.com/littlegem.html

So instead of using a speaker I will feed the output
into a headphone?

Yes, you might want a volume control before the input.
 A 100k should work, ears get signal path and ground, the wiper goes to the LG input.
 For CCW being turned Down, turn the pot all the way up [CW],> "That' lug sould get the signal input.