You can choose between a 1 x 12 or 4 x 12 emulation when being used with headphone, alternatively, you can use this to directly patch to a mixing console/audio interface for live or studio applications and treat it as a DI track to further add effects or amp sims. For safety reasons, always have a cabinet (load) attached to the head. Put the amp in standby for silent practice or direct recording. 

This output will both work with the amp fully powered or left in standby.