Some products in the Teufel Streaming series, including the Teufel One S, Teufel ONE M, CINEBAR LUX, and Teufel Streamer, have an additional function button with the symbol
Pressing this function button immediately switches to the Line-In, regardless of the previously selected source. So if a playback device is connected to the audio input (3.5 mm jack) on the back (labeled Line-In), it can be selected as the signal source at any time by pressing this button. Playback is controlled either via the app or the control buttons on the device.
Note: Originally, the function button was intended to be optionally assignable to other functions, as mentioned in some manuals. However, this was and is no longer implemented.