I am preparing to measure this little amplifier
The Wondom AA-AB31471 is a small, simple and efficient Class D mono amplifier module. It includes a TPA3110 TI chip to enable it to provide a power of 30W for an efficiency of 90%, as well as a precise sound reproduction.
www.audiophonics.fr
so I was seeking for a SMPS power supply with 19Vdc voltage. I found one in my stock, which was originally a PSU for my very old notebook. The PSU looks like this
and seems to be the same unit that is recommended for the small Wondom amplifier
sector-adapter-supply-100-240V-to-19v-34a
www.audiophonics.fr
So I have decided to try this power supply with my AIYIMA A07 and I was very happily surprised with the result.
This is a spectrum of 1kHz/20W/4ohm
Quite low distortion and please note total absence of mains spuriae harmonics. Of course proper wiring of the measuring system is necessary to get it.
This is THD+N vs. output power
And this is THD+N vs. frequency at 20W/4ohm
With this power supply, we get clean 20W/4ohm and acceptable 30W/4ohm. The PSU construction is rugged, well built, and the unit I have has been in operation since 2010.