The 722k audio outputs are set at line level output voltage and without a volume control. The line level is set so it does not distroy the audio component internal amp. Headphone, and speaker, outputs are at speaker level voltage output. Speaker level voltage is much higher than line level. If you were to connect a speaker level output device(722k) to an amp(tv), the amp could be damaged if the output device voltage past a set voltage the amp(tv) could handle. In order for you to listen using headphone the 722k would have to have an internal amp that controls the volume of the headphones. If you connect headphones using a y adaptor, you will have low to no sound from the headphones.