“Insanely low output impedance”

• The output impedance is typically 3 milliohms from DC to 80 KHz and supply line rejection is > 80 dB over the same bandwidth and is still > 50 dB at 1 Mhz.

• This demonstrates the regulator’s ability to manage the load, regardless of frequency.

• How is it measure? The output impedance of the SR voltage regulator topology was measured by loading the regulator output via a modulated high power current source at varying frequencies. The measurements were taken between the regulator output sense node and the 0v reference star. Obviously connecting equipment via lengths of wire is going to swamp the low output impedance of the regulator, however, the low regulator output impedance is still valid as it reduces interaction at the regulator end of the wire compared to a regulator with higher output impedance.”

— Jay Luong, Audiobacon.net

https://audiobacon.net/2018/07/11/paul-hynes-sr4-the-worlds-best-audiophile-power-supply/2/