There is no way for comfortable and easy way to meter input audio signal. (before recording). Mixer window with audio input track occapy too much space on screen. Audio track meters show input signal level only with “monitor” knob activated. Monitoring is bad while recording. I think that meter of armed for record audio track must switch to input signal independed of state of “monitor” knob.
You know you have 3 different mixers, just set one of them to display inputs only. Can’t get more easy and comfortable than that.