When Craig did his Sweetwater demo of the Singthing he had a Mic in, Guitar in, and headphones out. When I try to use headphones out to a powered speaker/mixer/pa it turns the Singthing monitor off. Was he not actually using the Sing, he was not using in ear monitors so one would assume he was sending the signal out via the headphones to the board or camera and using the Monitor. The manual does not say that headphones cancel the monitor.
Hey Steven, Yes you're correct that plugging in headphones will disable the on-board speaker in SingThing. This is by design, but I understand what you're getting at and have logged the ability to use headphones with the speaker active as a feature request for a future update. In Craig's demo, he was not using the speaker in the product, as they took the headphone output and sent that into the mixing board and PA of the hall they were in. Cheers