The amplifier is set up for a voltage gain of about 20, with a high pass filter to reduce the gain near DC. Because of this, DC offsets are not amplified so no audio coupling capacitors are used, which helps to keep the sound quality optimum and save large, costly non-polar caps on the speaker outputs.
http://www.andrewkilpatrick.org/mind/stereo_amplifier/
Most PCB amps that have been produced have been poorer than tube amps, for reasons having nothing to do with the PCB. Like plastic bobbins in transformers, this does nothing to change the tone. The other poor practices that go with a cost-cutting attitude that were introduced at the same time may, but PCBs are unfairly indicted.
http://www.geofex.com/Article_Folders/pt-to-pt/pt-to-pt.htm
A stereo power amplifier is limited in its output power by two main factors - the impedance of the load and the internal power supply voltage. To obtain more power, one has very limited choices - other than the purchase of a more powerful amp.
http://sound.westhost.com/project14.htm
A conventional common-drain MOSFET-based power op amp, with a simple and stable configuration, has a dynamic response identical to that of IC1. However, as a power amplifier, it exhibits a limited-output voltage swing that is typically less than either supply by 6V.
http://www.edn.com/archives/1994/092994/20di5.htm
The circuit is based on a simple inductor-capacitor filter circuit, and needs only a pot and a small light bulb to set and stabilise the oscillation. The frequency is fixed, and with a good inductor should be capable of very low distortion.
http://sound.westhost.com/project59.htm
This App Note describes a digital amplifier, which operates from13.5-Volt power source and outputs up to20W poor channel power.
http://www.tripath.com/downloads/EB_TA2020.pdf
A power MOSFET is biased using a pot (needed to correct for different device characteristics) so that the voltage at the drain is about 1/2 the supply voltage.
http://sound.westhost.com/project36.htm
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
A simple amp to build, uses commonly available parts and is stable and reliable.
http://www.sound.au.com/project03.htm
National Semiconductor Application Notes.
http://www.national.com/an/AN/AN-69.pdf