Since we own in our Lab the flagship Audio Analyzer APX555 from Audio Precision, we publish some measurement results from commercial devices.
Setup: loopback balanced (input and output connected) low distortion analog generator
1Khz from the analog generator
1Khz from the analog generator
It is essential for an audio analyzer to reach good analog performance over a wide input dynamic range and not at a certain level, only.
At the ultra low distortion area above 1V input level, you will see some fluctuation of the distortion readings. The APX555 uses internal attanuators for optimum ranges. If you need to measure below 0.00005% you will need to set even the APX555 to optimum levels manually. But typically you are more limited by shielding.
1Khz from the analog generator
Since THD+N includes distortion and noise the readings are slightly higher.
Beyond analog performance, the audio analyzer APX555 can generate comprehensive automatic reports with the "sequence mode".
Selftest of our audio analyzer APX555 with balanced loopback
Related links to high performance audio measurments
Selected Measurements in our LAb with our APX555 from audio precision