Parasound
Parasound Halo A 21+ Stereo Power Amplifier
Best high-performance amplifier for driving demanding, power-hungry audiophile speakers.
Experience unparalleled audio performance with the Parasound Halo A21+ Stereo Power Amplifier. Engineered by John Curl, this high-bias Class A/AB amplifier delivers a robust 300 Watts per channel into 8 Ohms, offering immense headroom and current for even the most demanding speakers. Its direct-coupled signal path ensures pristine sonic purity, while the over-engineered power supply provides unrestricted low-end response. Designed for audiophiles, the A21+ combines exceptional build quality with sophisticated sound reproduction for a truly immersive listening experience.
$5000.00
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Owner Satisfaction
4.7
/ 5
Category Rank
325
/ 1684
#325 in Power Amplifiers
Price vs Category Average
-39%
Below average
Power Output (8 Ohm)
300
/ W per channel
Who it's for
- Audiophiles driving power-hungry, low-impedance speaker systems
- Listeners seeking transparent, high-fidelity sound reproduction
- System integrators building complex, high-end home audio setups
Who should skip it
- Users with limited rack space or restricted shelf capacity
- Owners with enclosed cabinets lacking proper airflow
- Budget-conscious buyers prioritizing value over reference-grade performance
Performance breakdown
Power Delivery
Massive current reserves drive even the most difficult speaker loads effortlessly.
Sonic Transparency
Direct-coupled signal path preserves every nuance of the original recording.
Build Integrity
Over-engineered chassis and components ensure decades of reliable, heavy-duty performance.
Low-End Authority
Robust power supply delivers deep, controlled, and punchy bass response.
System Versatility
Bridgable mono mode and rack-mount options fit diverse high-end setups.
Signal Purity
Exceptional signal-to-noise ratio ensures a silent background for critical listening.
Key Specs
Power Output (8 Ohm)
300 W per channel
Power Output (4 Ohm)
500 W per channel
Power Output (1 Ohm)
1,000 W per channel
Bridged Power Output (1 Ohm)
1,000 W
Peak Current
60 A per channel
Frequency Response
5 Hz - 100 kHz
Total Harmonic Distortion
< 0.1%
Signal to Noise Ratio
> 112 dB
Features
- Designed by legendary John Curl
- High-bias Class A/AB operation
- Bridgable for 1,000W mono power
- Massive 60A peak current per channel
- Direct-coupled signal path for purity
- Independent power supplies for all stages
- Automatic turn-on via 12V trigger or audio
- Includes rack mount hardware
What customers say
The Parasound Halo A 21+ is widely regarded as a benchmark stereo amplifier, celebrated for its exceptional value and performance. Audiophiles consistently praise its immense power reserves, noting its effortless ability to control demanding speakers. The sonic signature strikes an ideal balance, offering musical warmth alongside the transparency needed for critical listening. Users frequently describe this unit as a transformative upgrade, often replacing much costlier equipment. Build quality is excellent, reflecting meticulous design. Despite its size, customers feel the A 21+ delivers performance rivaling amplifiers costing significantly more, establishing it as a reliable, long-term investment for serious audio systems.
Know before you buy
Yes, the A 21+ is designed for demanding speakers. With a peak current of 60 amps per channel and the ability to output 1,000 watts into 1-ohm loads, it provides the necessary stability and headroom for even the most power-hungry speaker designs.
The high-bias design allows the amplifier to operate in pure Class A at lower power levels, which provides the warmth and detail associated with Class A amps, while switching to Class AB for higher power demands to maintain efficiency and control.
Yes, the A 21+ is bridgeable. When configured in bridged mode, it can deliver 1,000 watts into an 8-ohm load, providing a significant power boost for users who need a dedicated monoblock setup.
Yes, the A 21+ features both balanced XLR and unbalanced RCA inputs. Using the balanced XLR inputs is recommended if your preamplifier supports them, as it helps reduce noise and interference over longer cable runs.
The amplifier includes a 12V trigger input, allowing it to automatically turn on or off in sync with your preamplifier or processor. It also features an audio-sensing turn-on mode if you prefer to have it activate automatically when a signal is detected.
Yes, the unit includes the necessary rack mount hardware. Given its weight of 71 pounds, ensure your rack system is rated to support the load and that you provide adequate ventilation for the amplifier's heat dissipation.
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$5000