Parasound Halo A 23+

A robust power amplifier

Parasound's Halo A 23+ offers high-end performance in a slim, rack-mountable chassis. This amplifier delivers 160 watts per channel, and it's stable at low impedance, so it can drive just about any pair of speakers you might wish to hook up. In bridged mode, it brings the hammer, putting out 500 watts into a single channel. All that power comes from a beefy toroidal transformer and a high-bias Class A/AB amplifier design.

This amplifier pairs up nicely with Parasound's P 6 stereo preamp for a sweet-sounding two-channel music system.

The large toroidal transformer inside Parasound's Halo A 23+ delivers 160 watts of clean power to drive your speakers.

Class A/AB operation for smoother sound

You don't see a Class A/AB amplifier every day, so let's break down the benefits.

Engineers and audiophiles generally agree that Class A designs offer the purest sound, but they tend to run hot and take up a lot of space. As a result, home audio amplifiers often use a compromise known as Class AB, which hands off part of the audio signal to a different set of output transistors at high power levels. AB can sacrifice a bit of signal purity, but it lets the amp run cooler and more efficiently.

So this Class A/AB amp operates in pure Class A mode up to a higher power level than most other amplifiers in its price category, before the second set of transistors kick in. The result is a sound that's smoother, less fatiguing, and more natural.

Convenient connections

On the back panel are balanced XLR and unbalanced RCA inputs for each channel, and each has its own individual gain control knob and loop output. There are also binding posts for connecting a pair of speakers. The amp can be rack mounted using the included ears.

The legacy of John Curl

The A 23+ features circuitry designed by John Curl, a legend in audio engineering. He started his career in the 1970s, designing tape and video recorders at Ampex, and he had a hand in building the Grateful Dead's famous Wall of Sound. Curl has worked with Parasound since 1989, designing all of their high-power amplifiers and more. The power supply, transistors, capacitors and other parts in the A 23+ were chosen to offer high performance at a reasonable price.