Looks like harmonics level in 5k-10k range could be a good indicator. Or how long the 3rd and higher harmonics are sustained. Violin at the top, guitar at the bottom (audio files in attachment):
Or at least not so directly. What the generator shows is the RMS of the signal. I think this formula applies here for the RMS of sum of signals:
RMS_tot = sqrt( RMS_1^2 + ... + RMS_n^2 )
RMS of a sine is A/sqrt(2) and we have 31 sines, so:
RMS_tot = sqrt( 31 * (A/sqrt(2))^2 ) = sqrt( 31/2 *...
There already is a topic about that (I think):
https://www.audiosciencereview.com/forum/index.php?threads/why-is-every-amp-on-this-polish-website-at-low-signal-output-20-db-worse-than-amirm%C2%B4s-measurements.57805/
It's Alsa telling the device what format to use. The available formats that the device is capable to deliver are listed in "/proc/asound/card0/stream0" (or card1 or card2 etc). And I think "stream0" is the standard file name for USB devices. For example:
]$ cat /proc/asound/card2/stream0...
Over 100 pages long thread and the answer was so simple :)
https://www.audiosciencereview.com/forum/index.php?threads/things-that-cannot-be-measured.20808/
I find it somewhat funny that some people worry, that the inaudible ringing added by linear-phase filters will somehow change their perception of the music but at the same time they seem to be OK with minimum-phase filters removing the ringing that is part of the genuine signal. (Admittedly...