TOPPING A90 Discrete / A90 Headphone Amp


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Our best-selling amplifier 

“Mr. Clean.” “The Giant Killer.” “The Best Amp Ever.” These are a few of nicknames the TOPPING A90, our best-selling amplifier, has gained since its release. At its most basic level, it’s a balanced amp and pre-amp with tremendously clean and powerful output. At its broadest level, it’s become the benchmark by which all other solid state amplifiers below $1,000 are judged.

D for Discrete

The A90 Discrete, or A90D, is an upgraded version of the groundbreaking A90. As its name suggests, the A90D uses fully discrete components in a complete redesign of the A90 NFCA module. Four discrete NFCA modules using 39 transistors each form the fully balanced amp architecture. The matched precision transistors ensure unparalleled distortion and noise performance. 

A90 Discrete vs A90

Besides featuring fully discrete NFCA modules, the A90D features a number of quality-of-life improvements that are lacking in the A90. These include an R2R volume relay, a remote control, a ground loop noise terminator switch, a 12V trigger interface, a redesigned UI, volume memorization, and more. The specs of the A90D are also slightly better. For a complete breakdown of the differences between these models, check out this comparison chart. 

Calling all cans

Planar magnetic, electrostatic, dynamic drivers, IEMs—pick your poison, the A90D can handle it. Thanks to its high output voltage, high output current, and low output impedance, the A90D can push loads of power into high-impedance full-sized headphones or pare that power back in order to drive sensitive IEMs. And with an ultra-low noise rating and high dynamic range, the A90D does it all without producing any audible noise. 

Say goodbye to ground loop noise

When multiple pieces of equipment are used in conjunction, ground loop noise can occur. Ground loop noise most often manifests as a buzzing or humming sound, which is capable of being loud enough to damage speakers. Although it's known to happen most often in single-ended feeds, it can happen in balanced feeds, too.

The A90D solves this issue with a GND/LIFT switch. When in normal use, set the switch to GND. If you encounter ground loop noise, set the switch to LIFT, which will change the ground point of the A90D from its chassis to the equipment it’s connected to, eliminating the noise. 

Pre-amp mode

With the A90D in pre-amp mode, connect a power amplifier to drive bookshelf, desktop, or floor speakers. You can also connect the A90D to the D90SE/LE DAC in pre-amp mode to create a complete high-end sound system. And with the included remote control, you can control it all from the comfort of your couch. 

12V trigger

Wouldn’t it be nice if every time you turned on the A90D, the TOPPING LA90 came on automatically, or vice versa? That’s possible thanks to the A90D’s 12V trigger interface. Set it to active (trigger out) or passive (trigger in), and it can be turned on and off synchronously with other devices equipped with a 12V trigger interface. 

R2R volume control

The A90D uses an R2R volume control composed of relays and resistor networks, bringing the advantages of precise control, longevity, and complete channel balance. 

Volume memorization

Set the A90D to memorize the output volume settings of the pre-amp, headphone amp, and PRE+HPA modes, and automatically restore to the last volume used when the same output is selected in the future. 

A90D Product highlights

  • Headamp/pre-amp
  • NFCA discrete modules
  • 9800mW x2 output power
  • Outputs: 4-pin XLR, 4.4 balanced, 6.35mm SE
  • R2R relay volume control
  • Ground loop noise terminator
  • 12V trigger interface
  • 2 gain settings
  • <0.000055% THD+N
  • 145dB DNR


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What’s included

  • A90D Headphone Amplifier
  • Remote control
  • AC cable
  • 6.35mm to 3.5mm adapter
  • User manual
  • Warranty card


  • A90 Headphone Amplifier
  • AC cable
  • 6.35mm to 3.5mm adapter
  • User manual
  • Warranty card

What pairs well

Featured Reviews

"Probably the best sound signature of any amplifier I've heard to date." -Joshua Valour

"I'm pretty sure the textbook hasn't been written yet. But if it has, only TOPPING has a copy of it." -Zeos Pantera

"This is the perfect amp for anyone wanting to get a completely dead-neutral reference sort of amplification." -DMS

"This is the best test bench amplifier that I've run across so far." -Joshua Valour

"How good's the TOPPING A90? F*****g good. F*****g real good." -Z Reviews

"Fully deserves my highest praise." -SoundNews

"The best headphone amp I've had the pleasure of listening to." -The Boomer Consumer

"For $600, you can't go wrong." -the Honest Audiophile

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TOPPING A90 Discrete / A90 Headphone Amp User Manual Download

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