Cheap Audio Ampflication for Piezo Buzzers 1: TDA2030 "Hailege"

I decided to see how low you can get in costs for amplifiers suitable to drive a piezo buzzer sound installation. Basically you get all sort of digital amplifier ICs soldered on a small board with a basic circuit around. This is the first one I'm testing which comes at ~2 EUR for a mono channel. The board is described as based on TDA2030. It can run off 6 to 12 V (I am using a 12V power supply), has four input pins for line signal and power, and a screw terminal for the amplified output. There is a small potentiometre that can be used to attenuate the amplification. I ended up having it turned down most of the way. The amplified signal is fed to a single piezo buzzer using an intermediary transformer coil designed for 100V technique, in this case achieving a better match between the typical output impedance of an audio amplifier (suitable to 4 to 8 Ohms) and the higher impedance of the piezos (around 200 Ohms can be measured at DC). With the forgiving test sound file of spoken word,