Some products in the Teufel Streaming series, including the Teufel One S, have an additional function button in addition to three station buttons for directly saving and then starting radio favourites.
Pressing this function button results in an immediate switch to the line-in, regardless of which source was previously selected. If a player is connected to the Line-In, it can be selected as a signal source at any time by pressing this key.
Note: Originally the function key should be optionally assignable with other functions, as is mentioned in some manuals. However, this was and is no longer implemented.