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 $4,500. Cost no object, huh? If every manufacturer built sub-$5,000 cost-no-object products, the audiophile landscape would be vastly different.

The A51 is a THX Ultra2-certified, five-channel amp churning out 250 watts per channel into eight ohms and 400 watts per channel into four ohms. The A51 is a high-bias Class A/AB operating amp in a direct-coupled design with no capacitors or inductors in the signal path, powered by a massive toroid transformer. The A51 uses a MOSFET driver stage complemented by a JFET input stage. The A51 features both balanced and unbalanced input connections, as well as 24-karat gold five-way binding posts. It features large heat sinks along both the right and left sides, as well as down the center of the rear panel, separating the inputs from the binding posts to dissipate some of that class A heat. The A51 has a 12-volt trigger, as well as a detachable power cord, and comes standard with rack-mounting equipment, which is almost unheard of with an amp costing as little as the A51.

Getting beyond its inner workings, one cannot overlook the visual statement the A51 makes in your rack. With its smooth silver casework and slightly curved façade, the A51 is nothing short of gorgeous and mates beautifully with the rest of the Halo line of products from Parasound.

High Points
• With 250 watts on tap, the A51 will power virtually anything you can throw at it and probably more, making it ideal for robust high-performance home theaters and/or multi-channel audio systems.
• The A51 has a rhythmically soulful sound with a tremendously rich and natural midrange. The upper frequencies are detailed and lush without being harsh or fatiguing, though they lack that last ounce of air and extension that costlier amps bring to the table.
• The A51's bass is well-defined and extremely textured and robust, though it's no Krell and will not plunge to never-before-heard depths. However, for a sub-5K amp, the A51 is among the best all-round performers you're bound to find.
• Dynamically and in terms of spaciousness, the A51 is amazing, doing equal justice to both music and movies.
• The A51's inputs and binding posts make cable management a breeze and keep your rack nice and tidy.

Low Points
• Because of its class A/AB design, the A51 does get a bit warm and should be installed in a properly ventilated space and/or rack.
• The A51 is large and heavy, though not as bad as some, and is best moved and/or positioned by two people.

Conclusion
With a sub-$5,000 asking price, the Parasound A51 is a tremendous amplifier. While its asking price is far from cost no object, its performance is on par with the best, mating a beautiful midrange and non-fatiguing top end to a lively and punchy bass section that, while not the deepest-plunging, is one of the most musical I've encountered in a long while. With reputation and reliability in tow, the Parasound A51 is a stunner in almost every regard.
Keyword: Parasound, Parasound Halo, Parasound A51, Parasound Halo A51, Parasound Amp Reviews, Parasound Reviews, Multi-channel amps, Home Theater Amps, Home Theater Reviews, THX, THX Ultra2, Krell, Mark Levinson, John Curl