This enhanced Tube Buffer needs higher voltages to work comfortably. Thus it is plus and minus 55V. It is also regulated, using an adapted version of the SuperReg, developed by the Vacuum State Electronics team headed by Allen Wright.source

This amplifier design really excels in simplicity and robustness, thanks to the
use of the TDA2030 or TDA2040 “power op amps”, The power supply of the amplifier is built with bridge rectifier and elcap capacitor. Further stabilization is not necessary because of the high supply voltage ripple rejection (50dB).
Here are some features :

• Short circuit proof outputs.
• Built in thermal protection.
• High supply voltage ripple rejection: no supply stabilization necessary

source

This is one of the stronger amps based on LM3886 application note. It supports stand-by and mute modes. The schematic is rather complicated, because there are some additional devices in the feedback and there are filters both on the input and on the output.The application note contains two alternative topologies: the first one is simple, the second one contains output DC error correction using a servo feedback. The funny thing is, there’s not just a single servo per channel - there are four of them, one for each power IC.source

This is a reliably high sound quality audio power amplifier project based on the National Semiconductor’s LM1875 IC. The circuit that we give is a similar form of the application circuit in the datasheet that NS provides. It is really easy to build and low cost. The voltage gain of the each monolithic channel is 27dB.source

Ultra-Linear operation provides a compromise between the high efficiency of tetrodes and the low distortion and uncritical load impedance of triodes.There is an undoubted advantage in modulator service because the matching of the modulator to the RF stage is not so critical and the screen (DC) supply is obtained “automatically” from the transformer.source