The front left, right, and center speakers do most of the heavy lifting in your surround sound system, and Parasound's Halo A 31 three-channel power amp has the juice to drive them very well. This 65-pound dynamo delivers 250 watts per channel with all three channels driven, and it's stable at very low impedances, so it's compatible with a very wide range of speakers. With its sheer power — and thoughtful circuit design courtesy of Parasound's audio guru John Curl — this amplifier delivers impressive volume, clarity, and dynamics with your surround sound speaker system.
Each channel features an unbalanced RCA and a balanced XLR input, with individual gain knobs with a -6/+6dB attenuation range. The amp offers three power-up options: manual, signal-sensing, and 12-volt trigger.
Class A/AB operation for smoother sound
The A 31 uses a Class A/AB power circuit. You don't see an amplifier described that way 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.
The legacy of John Curl
The A 31 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 31 were chosen to offer high performance at a reasonable price.
