I love the Australian journal Silicon Chip, but I love all those DIY electronics journals. And the good thing is that either parts to various projects may be bought or whole kits. A few of the PCBs offered for SC's projects have ended up in my place, and the board for the headphone amp is one of them.
This one is rather interesting. I can beef up some partis of the circuits and use it as a low power amp for speakers, or use it, un-modified, as a headphone amp. I have chosen to use it like that.
When I get the chassis ready I will look for a transformer small enough to fit in the chassis but big eneough
to power the transformer.
Its obvious that a wallwart is intended for the amplifier as there's a single 12V AC connection, followed by a voltage doubler that gives a plus- and minusvoltage.