Parasound Halo A 21+ 2-Channel 300W Stereo Power Amplifier, John Curl, Bridgeable

The Parasound Halo A 21+ is a stereo power amplifier designed by John Curl, delivering 300 watts per channel into 8 ohms and 500 watts into 4 ohms with both channels driven, and 1,000 watts bridged into mono. It is the upgraded successor to the original A 21, which had remained one of Parasound's best-selling amplifiers for over fifteen years.

Compared to the original A 21, the A 21+ brings a 20% increase in power output, larger filter capacitance (108,000 microfarads vs 88,000), a larger 1.3 kVA transformer, halved THD at full power (0.1% vs 0.2%), improved channel separation at 20kHz (70dB vs 63dB), and upgraded heavy-duty speaker binding posts inherited from the JC 5. The internal audio connections are gold on gold throughout. ProHiFi is an authorised Parasound dealer in India.

The circuit is high-bias Class A/AB with a direct-coupled signal path containing no capacitors in the signal path. Peak current capacity is 60 amps per channel, and the damping factor exceeds 1,100 at 20Hz. Each channel has its own individual gain control and loop output on the rear panel, providing flexibility for bi-amping and multi-amplifier configurations. The A 21+ is also bridgeable to mono, configuring left and right channels as a single 1,000 watt output.

Stereophile's Kalman Rubinson concluded it is the very model of a modern power amplifier, recommending it to anyone in the market for a stereo power amp, especially those who believe they must spend more. Future Audiophile compared its 0.1% THD at full power to pure spring water versus the bioswale output of poorly rated amplifiers. Positive Feedback called it an exceptional value achieved through decades of experience and John Curl's guidance.

Key Features

• 300W x 2 into 8 ohm; 500W x 2 into 4 ohm; both channels driven
• 1000W bridged mono into 8 ohm
• High-bias Class A/AB; designed by John Curl
• Direct-coupled; no capacitors in signal path
• 60A peak current per channel; slew rate greater than 130 V/microsecond
• 1.3 kVA toroidal transformer; 108,000 microfarad filter capacitance
• Balanced XLR and RCA inputs; per-channel gain control and loop output
• Heavy-duty 5-way speaker binding posts from JC 5; gold on gold connections
• SNR greater than 115dB A-weighted; damping factor greater than 1100
• 12V trigger and audio-sensing auto turn-on; rack mountable
• 448 x 197 x 508mm; 32.2kg; Black or Silver
• Stereophile Recommended Component; Positive Feedback Writers' Choice; Future Audiophile Recommended

Warranty:

3-year manufacturer's warranty

Why Consider the Parasound Halo A 21+

The A 21+ is the right choice for listeners who want a high-power stereo amplifier with John Curl's circuit design at a more accessible price than the JC 5. With 300 watts per channel, 60 amps of peak current, and stability into difficult loads, it drives virtually any loudspeaker with authority. Stereophile's measurement bench confirmed it exceeds its rated power significantly, clipping at 400 watts into 8 ohms. The bridged mono capability at 1,000 watts gives a clear upgrade path, and the per-channel gain control and loop outputs make it equally suited to bi-amping or professional installation. Paired with the JC 2 BP or any quality line stage, it forms a reference-level stereo combination at a price that Stereophile described as making it pointless for most listeners to spend more.

Ideal for

• High-performance two-channel systems wanting 300W per channel at a mid-range price
• Demanding speaker loads that benefit from 60A peak current and 500W into 4 ohms
• Systems pairing with the Parasound JC 2 BP preamplifier or Halo P 6
• Bi-amping configurations using the per-channel gain controls and loop outputs
• Listeners wanting bridgeable mono capability for a future 1000W upgrade path
• Home cinema front channels needing high-power stereo amplification

Technical Specifications