If you’ve ever worked with vacuum tubes, you’ll probably have a healthy appreciation for high voltage power supplies ... demonstrates with his tube preamplifier running from only 3.3 V.

The audio side of the preamp comes courtesy of a four-tube kit from tubes 4 hi-fi, in which we notice another tube as power supply rectifier. The case is a beautifully made wooden affair with a ...

Like the 9000Q preamp, the 9000P’s power supply has sophisticated mains filtering, boosting its sonic performance. The net result is an amplifier that Audiolab describes as “wide-ranging ...