a couple of years ago I purchased a “150-in-1” set in a wooden case on a fleamarket. The “IC” was a thinfilm module, the contacts were spirals (corroded, with a grey dust on it) which had to be connected with lots of wires… criss-cross, rather terrible. So I sold it again…
The next simple amplifier/driver IC was the TAA435, used in several portables and car radios in Europe.
Here is my more powerful amplifier with a TAA861 and the AD161/AD162 pair:
I preferred having a heatsink (no melting of the plastic cover) instead of a schematic, so I pasted the covers below the snapshot for better understanding. This amplifier will work best with a more powerful loudspeaker box. In my office I use two of these self made zero-cost speakers (12 x 19 cm = 4.7 x 7.5 inches) with a wonderful sound:
But who would like to use the Lectron design, perhaps this is a nice idea:
Using the “standard” Lectron loudspeaker block (with a modification) it might be useful to connect headphones as an alternative: