Audio Research VSi55 Integrated Amplifier.
The push-pull VSi55 delivers 50Wpc via output taps for both 4- and 8-ohm speaker loads. Audio Research calls the VSi55's design "enriched" class-AB1. This class-AB operation keeps a significant amount of current flowing through the tubes even when idle. This idle current is higher than average for a class-AB design, hence the "enriched" qualifier and a factory-set bias level of 65mA per 6550 tube.
The VSi55 accepts five input sources including CD, tun