Parasound Halo A31 Three Channel Amplifier

Parasound Halo A31 Three Channel Amplifier

********* The A31 is now only available in black. *********


The A 31 was designed in response to increasing demand for a three channel power amp that holds nothing back in power or performance.  The A 31 is identical in performance and sound to the award‐ winning Halo A 51.  Here are a few of the many applications for the A 31:


  • To power the front three channels of a home theater.  The surround or back channels can then be powered by a smaller 2ch Parasound power amp such as the Halo A 23.    This gives the greatest power to the front channels where it is needed the most.

  • To power the center channel and two surround channels.    This allows the Left and Right front speakers to be powered by a dedicated two channel power amp such as the Halo A 21, or better yet, two JC 1 monoblocks.  This is ideal for the music lover who is unwilling to compromise stereo reproduction.

  • To power the front three channels in an AV receiver‐based system.  The remaining surround and back channels can be driven by the receiver.  This assures you the best sound for the front channels while enabling the AVR to produce more power for the surround and back channels.


However you employ the A 31, you will be delighted by its impeccable sonics, striking authority and faithful reproduction of the smallest details.






  • 250 watts x 3 @ 8 Ohms / 400 watts x 3 @ 4 Ohms

  • Adjustable gain for up to +6db over THX Reference level

  • Unbalanced RCA and balanced XLR inputs

  • Circuitry designed by legendary John Curl

  • High bias class A/AB operation

  • Direct coupled (no capacitors or inductors in signal path)

  • Complementary MOSFET driver stage and JFET input stage

  • 24 beta-matched 15 amp, 60 MHz bipolar output transistors

  • 1.5 kVA encapsulated toroid power transformer with independent  secondary windings for each channel

  • 98,400 µF power supply filter capacitance

  • DC Servo and relay protection circuits

  • AC present, channel status, high temperature indicators

  • Heavy-duty 24k gold-plated 5-way speaker terminals

  • THX Ultra2 certified

  • Auto turn-on by 12v trigger or audio signal

  • 4u Chassis, carry handles, rack mounting adapter included






  • Continuous power output:250 watts RMS x 3, 20 Hz - 20 kHz, 8 Ω, all channels driven400 watts RMS x 3, 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

  • Interchannel crosstalk:> 78 dB at 1 kHz;> 63 dB at 20 kHz

  • Input sensitivity:1 V for 28.28 V (THX Reference)

  • 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

  • Dimensions:17-1/4" w x 7-5/8" h x 19-1/8" d, 7" h without feet

  • Net weight: 65 lb.

  • Shipping weight: 79 lb.