P451 Purifi MonoBlock Amplifier

The P451 is March Audio's first Purifi based mono-block amplifier. In a matching enclosure to the stereo amplifier range and DAC1, this simply elegant product is milled from solid aluminium with a tough anodized treatment. Exceptional fit, finish and build quality.

The Mono-block format eliminates any possibility of crosstalk potentially found in stereo amplifiers.  The dedicated and over-rated 1.2kW power supply minimises load related voltage modulation.  The format also allows placement at the speaker permitting speaker cables to be as short as possible.


Featuring the new Purifi 1ET400A technology and Bruno Putzeys' development of his previous Hypex nCore designs, the P451 delivers extraordinary low noise and distortion with further improved refinement in subjective audio quality.

The class leading technical performance delivers a neutral but captivating musical sound that will suit the finest partnering equipment.  Fully 2 ohm capable with ultra low output impedance, the P451 can deliver up to 450 Watts and 25 Amps ensuring tremendous grip and drive even with the most challenging of speaker loads.

The OPA1612 differential input buffer has been designed to extract the maximum performance from the 1ET400A module. Featuring very low noise LT3045/94 voltage regulators which also power the analogue sections of the 1ET400A.  The digital section of the 1ET400A is powered from a separate regulator.  Careful attention to board layout and component selection ensures lowest noise and distortion levels.

The P451 features touch power switch, balanced Neutrik XLR inputs (compatible with single ended RCA), and heavy duty tellurium copper silver plated ETI Research speaker binding posts.  High quality Canare speaker cable and Mogami signal cable is used internally providing the best signal integrity and shielding. Input RF filters ensure freedom from intermodulation.  Suitable for use directly driven from high quality DACs or Pre-Amplifiers.

Hand built and individually tested, the P451 is backed up with a 3 year warranty.


  • Power Output 

    • 2 Ohms - 450 W

    • 4 Ohms - 425 W

    • 8 Ohms - 227 W

  • Current Output - 25 Amps

  • THD+N 0.00017% / -115dB  (at 100 Watts RMS 4 Ohm Load)

  • Output Noise - 12uV

  • Signal To Noise Ratio - 131 dB(A)

  • Output Impedance - 70 uOhms

  • Input Impedance 20 kOhms

  • Audio Input RF Filter

  • ETI Research Tellurium Copper Silver Plated Kryo Speaker Binding Posts

  • 12 Volt Trigger Input

  • Frequency Response - 10Hz to 60kHz (+0/-3dB)

  • Voltage Gain 26.5dB - Custom gain settings can be implemented at manufacture. Please contact us for details.

  • Dimensions (w)190mm x (d)335mm* x (h)85mm**

* includes speaker posts

** includes feet