Also, if listening low, at say 60 or 70dB peaks or below, many loads with certain amps will have the possibility of THD and a noise floor becoming audible, especially when the music dips below peak, sometimes by 10 or 20dB+… depending on the DR and nature of the music. Intros and outros.

The THD+N of a DAC at 40dB down signal and the character of an amp at low levels into sensitive low impedance loads all add up.

And just as before, we then have people say things like, “well, the distortion and noise level that ASR says is the threshold actually doesn’t matter you can’t hear it anyway.” Have your cake and eat it too type of thinking.

Electrical math and performance are hard facts for circuits… looking into it properly for a more informative analysis is a lot more involved than a 1kHz test tone at unity gain and a couple levels sweeps for THD+N at 33 and 300 ohms.

The chart for the Apple usb-c dongle doesn’t go to 1 μW for some reason anyway. But we can extrapolate decently.

(I often listen to speakers at 60dB max c-weighted peaks, fwiw)