Skip Navigation

Integra ADM-20.4

Stereo power amplifier

| 1 question - 1 answer

Item # 164ADM204

In Stock

Add to Cart

Ask an expert

Our VA-based experts can help.




Our take on the Integra ADM-20.4

The Integra ADM-20.4 has plenty of power — 75 watts per channel into an 8-ohm load — to be the main amplifier in your home stereo system. If you choose to expand that system into multiple zones, it's ready for that, too. A stereo RCA output lets you daisy-chain additional amps to bring two-channel sound to one or more rooms throughout your home.

Extend your stereo setup to additional zones

The Integra ADM-20.4 has plenty of power — 75 watts per channel into an 8-ohm load — to be the main amplifier in your home stereo system. If you choose to expand that system into multiple zones, it's ready for that, too. A stereo RCA output lets you daisy-chain additional amps to bring two-channel sound to one or more rooms throughout your home.

Multiple power-up options

Ordinarily, you'd turn on your main amplifier with a remote control or go the old-fashioned route and manually push the button on the front of the chassis. In a multi-zone system, it's convenient to have some automatic turn-on options, which the ADM-20.4 provides. A switch on the back of the unit lets you choose — daisy-chained units can power up when the first amp comes on (voltage trigger), or they can wait until music starts to play (signal sensing).

Product Highlights:

  • 2-channel amplifier with all-analog circuits
  • WRAT (Wide Range Amplifier Technology) for clean, distortion-free sound
  • power output:
    • 75 watts RMS per channel into 8 ohms at 0.08% THD (both channels driven)
    • 65 watts RMS per channel into 4 ohms at 0.08% THD (both channels driven)
  • frequency response: 10-100,000 Hz (-3 dB)
  • signal-to-noise ratio: 110 dB
  • total harmonic distortion: 0.08%
  • stereo RCA input
  • stereo RCA output lets you daisy-chain additional amplifiers
  • three turn-on modes: signal-sensing, voltage trigger, and manual
  • gold-plated binding posts spaced to accommodate dual banana plugs
  • 12-volt control output
  • input level control on rear panel
  • fanless design with heavy-duty aluminum heat sink for cool, quiet operation
  • detachable AC power cord
  • 17-1/8"W x 5-1/2"H (including feet) x 12-1/2"D
  • weight: 17.6 lbs.
  • warranty: 3 years
  • Our 60-day money-back guarantee

What's in the Box:

  • 2-Channel power amplifier
  • 6' AC power cord
  • Instruction Manual
  • Product Registration/Warranty Information

Hands-on research

Product Research


2-Channel Power Amplifier: The Integra ADM-20.4 is a two-channel stereo power amplifier rated at 75 watts per channels (into 8Ω, @ 1kHz, with 0.08% THD) or 65 watts per channels (into 4Ω, @ 1kHz, with 0.08% THD).

Wide Range Amp Technology (WRAT): Onkyo's Wide Range Amp Technology (WRAT) circuit layout prevents phase shifting by pushing the roll-off point higher than the listening-level frequency. Amplifying sound without phase shift creates an uncommonly well-focused and realistic audio image.

Three-Stage Inverted Darlington Circuitry: An important upgrade to the core WRAT concept is Integra's Three-Stage Inverted Darlington Circuitry, a low negative feedback topology featuring a discrete triple transistor array to cut distortion and boost current flow to the speakers. As well as improving efficiency, transient response, and audio clarity, discrete transistors run cooler, extending the life of your output stage for more years of trouble-free service.

All Analog Circuitry: A standard integrated amplifier has the dual task of both processing and amplifying audio signals, and is therefore susceptible to interference from digital circuitry. As a dedicated power amp with all-analog circuitry, the ADM-20.4 is protected against digital interference. From input to output, signal purity is maintained at every stage of the power amp. When partnered with a quality pre-processor (sold separately), this unit offers all the benefits of pure analog amplification - a warm, musical, and full-bodied sound.

High Output Power Supply: A massive EI transformer delivers a steady supply of power to the speakers, while two large 10,000 μF capacitors, heavy-duty transistors, and low-impedance copper bus bars work in concert to enhance the power and fidelity of your audio sources. A heavy-duty aluminum heat sink keeps the unit running cool for superior reliability and longer life.

Rigid Anti-Resonant Chassis: Housed in a rigid anti-resonant steel-plate chassis and finished with a tough one-piece aluminum front panel, the ADM-20.4 is highly resistant to vibration.

Line In and Out: The Integra ADM-20.4 is equipped with a stereo RCA line-level input to connect your pre-processor or pre-amplifier (sold separately). Its also equipped with a stereo RCA line-level output to daisy chain the audio signal to another power amplifier (sold separately).  The line-level input and output RCA jacks are gold-plated for excellent signal transfer.

  • Input Level Adjustment: There is a rear-panel input level adjustment, so you can better match the output stage of your pre-processor or pre-amplifier with the input stage of the ADM-20.4.
  • Audio Signal Turn-On: You can set the power amplifier to automatically turn on when it sense an audio signal from it line-level input. It will not turn off until there is no audio signal input for 3 hours (Auto Standby) or your press the "On/Standby" button on the front-panel.

Binding Post Speaker Terminals: The stereo power amplifier is outfitted with a set of  gold-plated binding post terminals for connection of one pair of speakers (4Ω to 16Ω compatible). The binding post terminals will accept bare wire (up to 10AWG), pin-connectors, and banana plugs (single or dual). There is a rear-panel speaker impedance selector to switch between 4Ω and 8Ω capability.

  • 4Ω Setting: Use the 4Ω setting for loudspeakers that are 4Ω or greater, but less than 8Ω.
  • 8Ω Setting: Use the 8Ω setting for loudspeakers that are 8to 16Ω.

12V Trigger In/Out: The unit is equipped with a selectable 12-volt trigger input (3.5mm) and output (3.5mm) providing automatic power on/off with your home theater system.

Note: You can choose to use the 12V Trigger In/Out or the Audio Signal Turn-On, but you cannot use both.

Auto Standby: When the Auto Standby function is activated, the power amplifier will automatically enter Standby mode if there is no operation for 3 hours with no audio signal input.

Optional Rack Mount Kit: An optional rack mount kit (sold separately) provides a clean, finished look when installed in racks and cabinets.

Our Product Research Team

At Crutchfield, you'll get detailed, accurate information that's hard to find elsewhere. That's because we have our own in-house Product Research team. They verify what’s in the box, check the owner's manual, and record dimensions, features and specs. We stay on top of new products and technologies to help people make informed choices.

Q & A

Customer Q&A

Crutchfield asked  
Why did you buy this?

It was suggested by Francis from Crutchfield support great chat by the way he helped me a lot [ Jose  Nov 18, 2018 ]

1 question already asked

Sure. The Onkyo has both multi-channel and multi zone pre-amp outputs you can use to provide audio signal into the Integra amplifier. [ Ryan  Oct 03, 2018 ]  Staff