This was my first creation. I did not know a lot about electronics at the time, so it was very simple. An AC coupled darlington triple emitter follower, powered by a valve filament transformer. When hooked to output of pre-amp, this circuit definitely sounded "better" (if not louder) than the Trio Receiver that I was using at the time.

My first steel case.

Mmmm... note the emitter resistors painted black to aid heat dissipation!

output power:
250mW into 8R.