OK. I watched about half of the video. Thanks for sharing the link. Very interesting subject, but ultimately way advanced for most home recording enthusiasts.
It seems to me that his main point is to record at input levels that take advantage of modern digital formats especially using 24 bit recording and to identify the difference in metering practices of analog vs digital. When everything was in the analog domain they metered in RMS values because clipping peaks would simply cause low level distortion and gentle compression especially when recording to tape that in many ways was desirable because of the harmonic overtones that would be introduced into the recording as a result. But, with digital we must use peak metering because any peak that exceeds 0 dB will cause very nasty digital distortion that is not considered to be pleasant by anyone. So the old way was to push the input level as high as possible while now you really want to record at much lower input levels to take advantage of the available headroom that 24 bit recording allows us today.
Ultimately, that is why it is suggested to record (and I'm sure some pros will correct me here) at levels like -10 to -18 dBs. But really, you can always draw your fader down if you recorded too hot. There is a plethora of information about this on the web. Also, some of the things I mentioned before are why there are so many analog emulating effects. The reason is we want to replicate the sound that people are used to hearing from recordings of the past. Though those old recordings may not be accurate reproductions of the original sound, that is what people have come to expect a recording to sound like. So, the original purpose of recording was to remotely reproduce the experience of witnessing a performance, but now it has moved into a musical instrument of its own to make the recording sound the way we like and think it should sound.
I personally think that trying to tune your DAW's internal workings is a waste of time for the nonprofessional, and that one should instead spend more time knowing and understanding the gain structures required for using the gear they have. So, if you're trying to use a lot of external gear you need to make sure to watch their input meters to know that you're outputting the proper signal level for that equipment to and from your DAW.
But, to answer your original question...you just need to set the Input of all the tracks you're wanting to receive the signal to the output of your tone generator. You can do this from the Track Inspector or from directly in the Mixer. I think that meter settings are done from the top right drop menu inside the Mixer window if you want to select prefader metering. Good luck with this.
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