Four years ago, I bought an amplifier board online. The seller said its output was 70 watts and it would require a 3 amps 12-0-12 volts transformer. I did not know much speaker wattage and never built the amp.
Recently, I bought the biggest subwoofer (8-inch) I could get. A carpenter built the speaker box as per my drawings. I had two 3-inch full-range Philips speakers, which I used as satellites.
My original design was much more complicated but it was a lot of work and I simplified it with minimum parts. Still it has an MP3 media player, volume controls (also on the remote), FM radio, and two 5-volt dispensing USB ports (for, say, a Bluetooth reciever). I also added a jack input hanging outside from a hole (that also acts as the pressure vent) to reduce strain on the media player.
Later, I found the amplification was provided by TDA1544q IC. This is a car amplifier providing a total of 44 watts of power over two or four channels. The board uses two channels for the satellites and other two are bridged for the subwoofer.
The orientation of the pots is flimsy as they are separate from the amp board. The front panel is too thick. Currently, they are hanging from a piece of plastic.
This was the first time I worked with AC. I got a AC-compatible flip switch.
The amp was considerably compromised by me twice when I connected the amps to it in the wrong way. The caps exploded. I replaced them. With sloppy soldering, I damaged the volume control pins when I bought it. Once I connected the sound the wrong way and the subwoofer and one satellite became silent. It drove me mad before I figured it out.