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.

I am now comparing three boards, based on the PAM8610, TPA3310, TDA2030 chips. After I got a lot of background noise for the PAM8610, I figured that the amplification is actually too high, and compared to the previous test, I no longer use a coil transform to match the impedance better with the piezos. With a direct connection, you no longer get background hissing, but you need to drive the amp higher with the line signal. I run all three at 12V, but the line levels are set differently to better match the capabilities of each board. That is to say, they are not equally powerful at full level.

Here's a comparison of the three boards:

At the end of the video, you can hear again all three in succession, playing the same snippet. Note: volumes have been adjusted to match. The TPA3310 seems to vibrate the glass more, but I think it's a positive indicator for better bass reproduction, whereas the PAM8610 might appear more "neutral" but seems to have stronger distortion (to my ears).