Yo Rolland:
I have a small GK amp in my studio that I sometimes use to run an electric bass DIRECTLY into my multitrack recorder.
DIRECT OUT usually means that whatever you INPUT, bypasses the speaker; thus the speaker is passive when this bus is used. So, while wearing the headset, a pure sound is heard and there is no competition from the speaker.
It is a good feature and you can also use this bus to run input silently out into another speaker across the room for whatever reason.
Have fun and remember: busses are like a retirement fund: You put something in and get something out.
Green Hornet