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Estimated price (community-sourced)
Around — community and catalog average, updates slowly
The Parasound Halo A51 is a five-channel power amplifier designed by legendary John Curl, featuring THX Ultra2 certification for home theater excellence. It operates with high-bias Class A/AB circuitry, delivering 250 watts RMS per channel into 8 ohms and 400 watts into 4 ohms, all channels driven. The amplifier uses a 2.2 kVA encapsulated toroidal power transformer with independent secondary windings for each channel and a massive 164,000 µF power supply filter capacitance, providing a peak current capacity of 60 amperes per channel. Its direct-coupled design eliminates capacitors and inductors in the signal path for maximum purity. The complementary MOSFET driver stage and JFET input stage, along with 40 beta-matched 15 amp, 60 MHz bipolar output transistors, ensure exceptional sound clarity and power handling. Features include balanced XLR and gold-plated RCA inputs, a ground lift switch, heavy-duty 24k gold-plated 5-way speaker terminals, and auto turn-on via 12V trigger or audio signal. The amplifier also includes DC servo and relay protection circuits, along with indicators for AC presence, channel status, and temperature. Its robust 4U chassis includes rack mounting hardware and carry handles, weighing 80 lbs. The Halo A51 is praised for its uniform power delivery across all channels, low distortion (<0.2% THD), high signal-to-noise ratio (112 dB), and wide frequency response (5 Hz to 100 kHz). It is suitable for demanding home theater and high-fidelity audio systems, providing both musicality and dynamic power.
Amplification power output and characteristics
Analog signal output specifications
Input and output connections
Size, weight, and appearance
Specifications are community-contributed and may not be accurate or complete. Verify all details with the manufacturer before making purchasing decisions. Terms & Conditions
Components that show up alongside the Halo A 51 in real systems. A verdict means the pair has been checked for compatibility and headroom — open it to see how the two get along.
The closest alternatives on specs, description and the systems they turn up in, with the specs they share set side by side.
The A-52+'s power @ 8ω is 180W against the Halo A 51's 250W and its power @ 4ω 255W against 400W. Both share signal-to-noise (112 dB) and damping factor (>1000).
Both turn up in the same documented systems.
The Halo A 31 matches the Halo A 51 on power @ 8ω (250W), power @ 4ω (400W), signal-to-noise (112 dB), and damping factor (>1000).
Both turn up in the same documented systems.
The GFA-5705's power @ 8ω is 200W against the Halo A 51's 250W, its power @ 4ω 300W against 400W, its signal-to-noise 106 dB against 112 dB, and its damping factor >300 against >1000.
The Cinenova Grande 7 BR's power @ 8ω is 360W against the Halo A 51's 250W, its power @ 4ω 610W against 400W, and its signal-to-noise 121 dB against 112 dB. Both share damping factor (>1000).
Both turn up in the same documented systems.
A21+
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