Question Can I use the headphone jack as a monitor while using the balance DI out to go to the front of house PA Also can I use the headphone jack while using the Digital out for instance using the head essentially as a Preamp Direct box while using the headphone jack to hear myself.  This would be with no speakers only the head. 

The headphone output cuts the speaker output only - The pre-amp out, DI out and digital OUT are still fed wit the bass signal when connecting the headphones.