SMSL H400 Headphone Amplifier

$433.50 $510

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Powerhouse Performance in a Compact Design

If your old amp has been struggling to keep up with your power-hungry cans, it’s time for an upgrade. The H400 laughs in the face of high impedance, pushing out up to 15W per channel at 16Ω. Those 600Ω studio monitors you’ve been eyeing? They’ll finally sound the way they’re supposed to. And for those days when you just want to kick back, the full-function remote control puts all the power in your hands—literally. With a high-efficiency, low-noise power supply tucked inside, the H400 runs cool and quiet, even when you’re cranking it up for hours on end.

Serious power for your headphones

Ever tried to drive high-impedance headphones with an amp that’s barely awake? We’ve all been there—flat sound, no dynamics, frustration. The H400 laughs in the face of underpowered setups, pushing up to 15W per channel at 16Ω. Even those 600Ω studio monitors won’t make it break a sweat. Expect vibrant sound, punchy bass, and an overall kickass audio experience.

Gain for days

One gain fits all? Nah. The H400 understands that sometimes you need to dial it back or crank it up. With high, medium, and low gain settings, you can customize the output to match your headphones and mood. Whether you’re whispering through a pair of sensitive in-ears or blasting a set of demanding cans, the H400 has you covered.

No pops, no clicks, just clean transitions

There’s nothing like the heart-stopping pop when you turn on your gear. It’s a jarring reminder that maybe your setup isn’t as refined as it could be. The H400 keeps things classy with a design that eliminates power-on and switching noise. Power it up, flip those gain settings, and enjoy the silence—until the music kicks in.

A preamp with a purpose

Versatility? The H400 nails it. Besides driving your headphones, it doubles as a high-end preamp. Connect it to your power amps or active speakers, and you’re in business.

Lazy-day approved

You know what’s annoying? Having to get up to tweak your amp’s settings. The H400 takes that inconvenience and throws it out the window. Its full-function remote lets you control everything from volume to gain without moving an inch. Perfect for those “I’m not getting up” listening sessions.

Fully balanced design for pristine sound

The SMSL H400’s fully balanced discrete component design keeps things in check, delivering cleaner sound, sharper separation, and a listening experience that feels like you're right there with the music.

Electronic relay volume control

Remember the days of scratchy volume pots and channel imbalance? Yeah, those are over. The H400 uses electronic relays for volume control, ensuring precise adjustments and flawless sound quality at every level. 

Aluminum housing and low-noise power supply

Looks aren’t everything, but they don’t hurt either. The H400 sports a sleek, silver aluminum body that’s right at home on any desk. And with its high-efficiency, low-noise power supply, it stays cool and quiet—letting your music take center stage without a hitch.

Product highlights

  • High power output: 15W at 16Ω, 7.5W at 32Ω, 1W at 300Ω, and 550mW at 600Ω.

  • Three-tier gain control: Adjust to high, medium, or low based on your headphones.

  • No popping noise: Smooth, noise-free power on/off.

  • Preamp function: Use as a preamp for other gear.

  • Remote control: Full-featured remote included.

  • Balanced design: Fully balanced discrete component setup.

  • Electronic volume control: Precision volume adjustments with electronic relays.

  • Sleek and compact: Silver aluminum body with an efficient power supply.


  • Input Method: Balanced, unbalanced.

  • Earphone Output Method:

    • 4.4mm Balanced

    • XLR Balanced

    • 6.35mm RCA

  • Preamp Output Method: Balanced, unbalanced.

  • Output Power:

    • 16 Ω: 15W x 2

    • 32 Ω: 7.5W x 2

    • 300 Ω: 1000mW x 2

    • 600 Ω: 550mW x 2

  • SNR: 133dB.

  • Dynamic Range: 133dB.

  • THD+N: -123dB, 0.00006% (1kHz, 32 Ω).

  • Input Impedance: 47kΩ.

  • Headphone Output Impedance: Almost close to 0 Ω.

  • Preamp Output Impedance:

    • Balanced: 44Ω.

    • Unbalanced: 22Ω.

  • Frequency Response: 20Hz - 100kHz (±0.5dB).

  • Gain:

    • Balanced:

      • Low: -5.8dB.

      • Medium: 6dB.

      • High: 20.4dB.

    • Unbalanced:

      • Low: -11.8dB.

      • Medium: 0dB.

      • High: 14.4dB.

  • Consumption (EN60065): <50W.

  • Standby Power Consumption: <0.5W.

  • Volume: 10 x 1.8 x 7.4 inches (254 x 46 x 189 mm).

  • Weight: 4.47 lbs (2.03 kg).

What’s included

  • SMSL H400 Headphone Amplifier

  • Remote control

  • Power cable

  • User manual

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