If you really enjoy listening to music at home, then you would want an audio system that produces the most pleasing sound. You would want a system that does not induce unwanted artifacts into the sound, a system that simply amplifies signals without altering or manipulating the signal. Of the various class amplifiers Class A is the most simple linear method that does not manipulate the signal. It is the reason that Class A amplifiers are the choice of many audio aficionados.
Power amplifiers that drive speakers have three common classes, Class A, Class AB and Class D. There are also other classes similar to Class D operation. Low-level analog amplifying stages are normally operated Class A. It is power amplifiers where various classes of operation come into play. Traditional Class A operation of power amplifiers requires the output stage to draw a significant amount of current even if no signal is present. This results in Class A amplifiers that can double as space heaters. Class AB push-pull was developed as a means to increase power with less current, but manipulates the amplified signal altering the original signal. Class D and similar classes provide the highest efficiency, but also manipulate the signal by converting the analog signal into a stream of pulses that modulate current. The different classes of operation are briefly compared in the link below. You really do not need a lot of amplifier power to achieve loudness, it depends on the type of speakers you use. See power versus loudness below.
Audio Entity is a place where old technology is given new life. Although custom built amplifiers may be offered from time to time the primary focus is design of circuits suitable for home builders. With relocation to the Philippines shipping heavy items such as an amplifier to the U.S. may be prohibitively expensive. Shipping custom amplifiers to Europe is not possible because all soldering is done with long life lead based solder.
Amplifier designs are a combination of standard and specialized circuits all tested for performance and reliability. Designs are Class A single ended output. A responsive bias configuration is under development for higher efficiency Class A. In effect it is a tracking bias supply. Output tube current is reduced at lower volume levels allowing the output tubes to run cooler. Lower current also reduces power consumption of the amplifier. This is not a new concept, what makes this project unique is that the design will be available for hobbyist in construction of amplifier projects. Prototype circuit boards have been made up and are performing as expected. It will take time before they can be tested in an actual amplifier.