Aaah, I see. I don't think there is one. 2.1 line out is 3.2V rms max SE and 6.4V Balanced: (2) New feature - Line Out mode Press the UP button all the way up. When you see the original signal mode LED change to Light Green. GO2Pro and GO2A is entering Line Out mode which totally by-pass the volume control and designed to connect directly to Headphone Amp or Pre-amp. Max Vrms on Singled-ended: 3.2V rms Under 1.5 max SE would be 2V and Balanced 4V on high gain.