In the single channel supply I'm using a pair of LM2672-ADJ 1 amp regulators, pretty much cookbook buck regulators, but the tricks are in
keeping the noise under control. All parts with the exception of the power transformer are off the shelf, which is nice.
In the dual channel supply I use an LT1244 with custom inductors for the gate drive, transformer and output filter. The common-mode filter on the line side is a Panasonic part. It's sort of expensive with the custom wound parts but it all fits and runs clean and quiet. This is an off-line filter, which for those not familiar with switchers, means the power line ac is rectified to make about 330Vdc, which means a voltage doubler on 110, and right off the line at 220, this dc is then chopped at high speed, 150kHz, stepped down to approximately the output voltage, rectified, filtered, with a portion fed back through a linear opto-isolator back to the control chip to set the output voltage. Only one polarity of output voltage is referenced, but since the audio circuitry is class-A and very symetrical load wise, that's all I needed.
Keeping 150kHz that is whacking around at those voltages from getting into everything and out beyond is all part of the fun. I learned a lot about keeping loops short, ground planes, and all the issues about dealing with creepage distances and other fun parts of high voltage stuff.
Hetrodynes? We don' need no steenkin' hetrodynes...