Parasound Halo A23+ Stereo Amplifier - Black

Audio Performance

Powerful, Clean Amplification — 160 watts per channel into 8 ohms (240W into 4 ohms) with distortion below 0.06% at full power. That’s enough juice to fill a large room and still have headroom to spare for dynamic peaks in your music.

Bridgeable Mono Mode — Flip a switch and combine both channels into a single 500-watt mono amplifier. This is ideal for powering a demanding speaker or subwoofer with maximum authority.

High Current Output — With 45 amps of peak current per channel, the A23+ can handle speakers whose impedance dips to very low levels without breaking a sweat. Difficult loads that make lesser amps struggle are no problem here.

Ultra-Low Distortion — Total harmonic distortion (THD) is less than 0.03% at typical listening levels. In simple terms, the amp adds almost nothing of its own character to the music — what goes in is what comes out.

Excellent Channel Separation — Crosstalk between channels is better than 85 dB at 1 kHz and 70 dB at 20 kHz. This means the left and right channels stay cleanly separated, preserving accurate stereo imaging and a precise soundstage.

Circuit Design

John Curl-Designed Circuitry — The audio circuits were designed by John Curl, whose amplifier designs are used in professional studios worldwide. The topology uses a JFET input stage, MOSFET driver stage, and 12 beta-matched bipolar output transistors per channel — each selected for optimal performance at its stage of the amplification chain.

Direct-Coupled Signal Path — No capacitors or inductors sit between the input and speaker terminals. This “direct-coupled” approach means the signal passes through the amplifier with minimal alteration, resulting in cleaner bass, more natural midrange, and extended highs.

High-Bias Class A/AB Operation — The amp operates in pure Class A at normal listening levels for the most natural sound, then seamlessly shifts to Class AB at higher power levels for efficiency. Parasound’s exclusive bias circuit ensures the amp sounds its best from the moment you turn it on — no warm-up wait required.

Power Supply

Robust Toroidal Transformer — A custom-made, 1.1 kVA encapsulated toroidal transformer with independent windings for each channel provides quiet, stable power. Independent windings help reduce crosstalk between channels for better stereo imaging.

Massive Filter Capacitance — 54,400 µF of filter capacitance (a 35% increase over the original A23) stores energy for demanding musical peaks, ensuring the amp delivers controlled, dynamic bass even during the loudest passages.

Connectivity

Balanced & Unbalanced Inputs — Both balanced XLR and unbalanced RCA inputs are provided. Balanced connections offer lower noise and a 6 dB gain advantage. A rear-panel switch optimizes the signal-to-noise ratio for whichever input type you’re using.

Per-Channel Gain Controls — Rear-panel gain knobs let you fine-tune the input sensitivity of each channel independently — useful for level-matching in bi-amp setups or multi-room systems.

Loop Outputs — RCA loop outputs pass the input signal through so you can connect additional amplifiers or a subwoofer without needing extra outputs from your preamp.

12V Trigger & Auto-Sensing — The amp can turn on automatically when it detects a 12V trigger signal from your preamp, or when it senses an audio signal. A trigger loop-out lets you daisy-chain multiple components. No extra remote needed.

Gold-Plated 5-Way Speaker Terminals — Heavy-duty, 24k gold-plated binding posts accept banana plugs, spades, or bare wire for secure, low-resistance speaker connections.

Design & Build

Refined Halo Aesthetics — Slim aluminum end caps with a gold metallic accent stripe, an engraved metal “Parasound” badge, and gold feet on the black finish give the A23+ an elegant, modern look that fits right in with any high-end system.

Slim, Rack-Mountable Chassis — At just 2U (3.5”) tall, the A23+ slides easily into a standard 19” rack with the optional HRA 2 rack mount kit. It’s also right at home on a shelf or audio rack.

Vacation Switch — A rear-panel master AC switch completely disconnects power when you’re away for extended periods, saving energy and protecting the amp.

Power Output — Stereo (0.06% THD)

• 8Ω, both channels driven 160 W × 2
• 4Ω, both channels driven 240 W × 2

Power Output — Bridged Mono (0.06% THD)

• 8Ω 500 W × 1
• Bridged 4Ω operation is not recommended

Power Output — Stereo (0.9% THD)

• 8Ω, both channels driven 210 W × 2
• 4Ω, both channels driven 300 W × 2

Power Output — Bridged Mono (0.9% THD)

• 8Ω 600 W × 1

Performance

• Peak Current: 45 A per channel
• Slew Rate > 130 V/µs
• Frequency Response 5 Hz – 100 kHz (+0/−3 dB)
• THD (full power) < 0.06%
• THD (typical listening) < 0.03%
• IM Distortion < 0.04%
• TIM Unmeasurable
• Crosstalk (1 kHz / 20 kHz) > 85 dB / > 70 dB
• S/N Ratio (A-weighted) > 112 dB
• Damping Factor (20 Hz) > 800
• Total Gain 29 dB

Inputs & Outputs

• Inputs 1 × balanced XLR pair, 1 × unbalanced RCA pair
• Input Impedance (unbalanced / balanced) 33 kΩ / 66 kΩ
• Input Sensitivity (28.28V into 8Ω) 1 V (unbalanced); 1 V per leg (balanced)
• Loop Outputs 1 × RCA pair
• Speaker Outputs 1 pair, 24k gold-plated 5-way binding posts
• 12V Trigger In & Out (3.5mm)

Power

• Standby 1 W
• Idle 75 W
• Maximum 800 W

Physical

• Width 17¼”
• Depth (without / with cables) 15¼” / 17”
• Height (with / without feet) 4⅛” / 3½” (2U)
• Weight 27 lbs

All power measurements at 120 VAC, RMS continuous, full audio band (20 Hz – 20 kHz).

What’s in the Box

• Parasound Halo A23+ Stereo Power Amplifier
• Detachable AC power cord
• Owner’s manual

Note: Interconnect cables, speaker cables, and the HRA 2 rack mount kit are sold separately. Verify complete packing list with manufacturer for the latest details.