we managed to get about 0.02% total harmonic distortion at 30 watts with a ±25v power supply into 8 ohms.
http://www.4qdtec.com/pwramp.html
This three-transistor amplifier delivers about 2 watts to an 8 ohm speaker.
http://www.wenzel.com/pdffiles/speakamp.pdf
Based on the National Semiconductor LM3876. This device is capable of delivering as much as 56W of continuous average power into an eight ohm load with 0.1% THD from 20Hz to 20Khz.
http://www.web-ee.com/Schematics/45WattAmp/45W%20amp.htm
http://w1.859.telia.com/~u85920178/use/afamp-4w.htm
100-Watt basic power amp that has better musical quality than the standard STK module amps used in practically every mass market stereo receiver manufactured today.
http://www.ee.washington.edu/circuit_archive/circuits/km241.html
can provide much more simply by increasing the power supply voltage. The available output power is limited by the power supply. Up to 70 watts output has been achieved with this topology.
http://members.tripod.com/michaelgellis/audioamp.html
design without a power transformer.
http://www.enteract.com/~jbyrns/25L6page.html
this circuit provides 16 watts of amplification. it is built using two LM383 power audio amplifiers.
http://www.reconnsworld.com/audio_16wattamp.html