Würth Elektronik ANP125 - Capacitors don’t cause any appreciable signal distortion

[EdGr]

Not forget that THD not only depends on frequency but also on power. Amps should not have higher THD at low power than on higher power.

This is mostly a consequence of THD being expressed as a percentage. A fixed voltage error around cut-off will be a higher percentage of a 4V signal than a 20V signal. The voltage error is inherent to class AB. Its severity depends on the magnitude.
Ed