Badly assembled. Cut corners. Cannot possibly have the rating advertised.
Inside is a Tripath TA-2020A chip, which cannot exceed 20W (the product claims 90W). It's supplied with a 12V@2A power adapter, so theoretically it cannot even exceed 24W. It's poorly hand soldered, and the inductor (for smoothing the power supply for sudden loads) was replaced with a short wire. A 220uF capacitor was installed on the spot labelled 470uF. It's also designed to shutdown at 12V instead of 13.4V, so you get less sound out of it.
I have a Lepy LP-2024A+ and I can tell that the PFA300 muffled the vocals and high frequencies. I got much deeper bass and high clarity from LP-2024A, but I couldn't get the voice/treble to sound as clear on the PFA300.
The LP-2024A is cleanly wave soldered and it's easy to modify (replace with better parts) as it has quite a bit taller. At least the screw holes are flushed for LP-2024A while the PFA300 is boderline aligned enough to fit (some screws has to go in at an angle).
The PFA300 is made by lazy designers using from junk parts. This unit is going to trash.