The H6 Line Out is an unbalanced stereo 1/8" phone jack, located on the bottom of the H6, beneath the LCD display. It carries the analog stereo output signal, as determined by the H6's internal mixer.
The H6 USB port, located on the side panel to the right of the LCD display, provides a digital output of either a stereo mix or the six individual input signals, depending upon the setting of the "Audio Interface" function in the USB menu.
In addition, the H6 provides a headphone output with a dedicated volume control, located on the side panel to the left of the LCD display. Connect your headphones to the stereo 1/8" mini phone jack for private monitoring of the stereo output signal.
The H6 even has a built-in speaker, located on the underside of the unit, for fast monophonic monitoring of the recorded signal without the need to make any connections whatsoever. This speaker is automatically disconnected when connection is made to either the Line Out or Headphone output.