THX Ultra2-Certified Parasound A 51 Five-Channel Power Amplifier Brings the Cinema Home: John Curl Circuitry, Huge Output, Audiophile Engineering Deliver "Thunder and Lightning"
The Parasound A 51 five-channel power amplifier has been unchanged and in constant production for more than 15 years. It also has earned rave reviews by more than a dozen global press outlets – Stereophile, What Hi-Fi?, Home Cinema Choice, and Home Theater Review included. Such is its one-two-punch ability to deliver clean, effortless power that drives even the most demanding speakers with graceful ease and to present the information, detail, and dynamics contained in soundtracks and music in vividly realistic fashion. This 78-pound brute remains a benchmark in (and above) its price class and handles both parts of the sonic spectrum.
Featuring John Curl circuitry and ultra-high-bias Class A/AB operation, the THX Ultra2-certified A 51 outputs 250Wpc RMS into eight ohms. With a measured THD of less than 0.2% at full power and direct-coupled topology, it plays with cinema-like excitement and involvement. A complementary MOSFET driver stage and JFET input stage, 40 beta-matched 15A/60MHz bipolar output transistors, and a massive 2.2kVA encapsulated toroidal transformer with independent secondary windings for each channel account for its sonic prowess. Factor in 164,000uF power supply filter capacitance and DC servo and relay protection circuits, and it's even easier to see why A 51 proves a master of its domains.
Connecting your gear to A 51 – supplied with carry handles and a rack-mounting adapter – is a breeze. Five balanced XLR inputs with discrete circuits and five gold-plated RCA inputs accompany five pairs of heavy-duty, 24k gold-plated five-way speaker terminals. You also have the option to auto turn-on A 51 via 12V trigger or audio signal. Parasound's five-year warranty and our 100% Music Direct Satisfaction Guarantee give you every reason to audition A 51 in your own home to hear the "sweetness and light" and "thunder and lightning" that caused Stereophile critic Barry Willis to purchase his review sample.
"If that 2-channel test drive had me thinking about buying the A 51, the multichannel experience made me want to slap down my Visa card. With music, the A 51 radiated sweetness and light. With action films, it rained thunder and lightning. There aren't many amplifiers that can so effortlessly cover both ends of the sonic spectrum."
– Barry Willis, Stereophile Guide to Home Theater
"I'd rate the A 51 as one of the most transparent power amplifiers in its class. It has genuine power and authority, and delivers the kind of visceral kick that makes action films swing along with panache."
– Alvin Gold, Home Cinema Choice, five-star review
"When it comes to high-performance, high-value power amplifiers, few do it better than Parasound. The A51, which is part of Parasound's Halo line of cost-no-object products designed in tandem with audio legend John Curl, has benchmark levels of performance, yet costs a reasonable [$4,995]. Cost no object, huh? If every manufacturer built sub-$5,000 cost-no-object products, the audiophile landscape would be vastly different."
– Home Theater Review
"Robust engineering rather than radical technology sees the THX Ultra 2-specified A 51 power amplifier through the day."
– Paul Miller, Hi-Fi Choice, Editor's Choice
"From the outset, I have to say that the Parasound A 51 multichannel amplifier delivered impressively clean, effortless, detailed sound."
– Perry Sun, Widescreen Review
"The A 51 has so much grunt, grip and grace, you have to restrain yourself from cranking up the volume until the walls start to ripple Matrix style."
– David Vivian, T 3 (UK)
250 watts RMS x 5, 20 Hz - 20 kHz, 8 Ω, all channels driven
400 watts RMS x 5, 20 Hz - 20 kHz, 4 Ω, all channels driven
Current capacity: 60 amperes peak per channel
Power bandwidth: 5 Hz - 100 kHz, +0/-3 dB at 1 watt
Total harmonic distortion: < 0.2 % at full power
IM distortion: balanced 16 V rms: < 0.04 %
Slew rate: > 130 V/µsecond
Dynamic headroom: > 1.5 dB
> 78 dB at 1 kHz;
> 63 dB at 20 kHz
Input sensitivity: 1 V for 28.28 V, THX Reference Lev
Input impedance: 47 k Ω unbalanced; 94 k Ω balanced
S/N ratio: 112 dB, input shorted, IHF A-weighted
Damping factor: > 1100 at 20 Hz
Voltage: 110V - 120V
Dimensions (WHD): 17-1/2" x 7-5/8" x 20"
Weight: 80 lbs.
User Manual (PDF, 942 KB)