In the nineties I built a class A power amplifier based on an article in the November 1985 edition of the Dutch electronics magazine Radio Bulletin. In 2000 I reproduced the article on my web site and added photos and extra schematics for a stabilized power supply for the preamp stage. Although some of the components are probably not available and the original website is long gone (archived on the WayBackMachine), I found it useful to repost the Dutch article: Klasse A-versterker van 20 Watt