The datasheet for the TDA7056 actually shows how to apply the integrated circuit. I also found some other application somewhere else (I forgot where though) and modified the original application with a few little details. I bought the parts and a project box and started working on this stuff.
The Vcc can be anywhere between 3V and 12V, according to the datasheet - I used 9V, 5V, and 3V, and felt little meaningful difference in the output; I finally settled for two 1.5V AAA batteries because I had the box for them at hand, and I have a lot of those batteries. I also added an on-off switch that completely cuts off the Vcc and the ground, but did not include it in the schematic, because it's a bit crowded as it is.
... that was actually in the summer. I failed miserably. First, I broke off two legs of my IC and decided to get a new one. Then, I worked on it all day and when I was done it didn't work, and I had completely no idea why. So I took a couple of weeks away from the project. I returned to it later on, only to measure some stuff, change some wires, get really frustrated and quit for a little longer. This repeated several times. Also with each time I inadvertently messed up the box a little, e.g. by sticking a soldering iron to the side by accident, or by spilling some glue on it.
Alas, this week I sat down, took everything apart, then reworked the schematics and assembled the thing again with some different parts. I tried to get every little element neatly into the box, painstakingly checking each connection to see that the solder was done ok. This worked mostly. And at the end I got tired and confused and a lot of little problems ensued with connections. At one point the circuit picked up radio even. And I screwed up the box again too.
Still, I managed. Here are some pictures:
My plans for using it include... nothing very much. This was a point of honour rather than a practical venture.