I wanted to point out that this condition is easily replicated since the mixer always starts with channel 1 selected, and if the channel is assigned to USB and the RTA is enabled, this is the screen that is shown upon bootup, probably due to the fact that the USB stream is totally silent in that moment, so the RTA isn't initialized with proper silence (sample contente zeroed). If the channel is assigned to an analog input, the RTA starts low because the analog input is actually generating a low-level audio signal even when no audio is present at the physical input.
