{"product_id":"smsl-h400-mk2-headphone-amplifier","title":"SMSL H400 Mk2 Headphone Amplifier","description":"\u003ch1\u003e\u003cstrong\u003e18W Gallium Nitride Balanced Amp\u003c\/strong\u003e\u003c\/h1\u003e\n\u003cp\u003eThe SMSL H400 MK2 is a compact desktop headphone amplifier and preamp built around a fully-balanced discrete architecture, 14 OPA1612A operational amplifiers, three selectable gain levels, and a custom low-noise gallium nitride power supply. Balanced and unbalanced inputs and outputs give it the flexibility to serve sensitive IEMs, full-size headphones, and a dedicated desktop audio system.\u003c\/p\u003e\n\u003ch2\u003e\u003cstrong\u003eFully-balanced amplification\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eThe H400 MK2 uses a fully-balanced discrete component architecture with symmetrical signal paths designed to reduce interference throughout the amplification stage. Its balanced headphone output reaches up to 18W per channel into 16Ω, giving the amplifier substantial power for demanding headphones while selectable gain settings provide finer control with more sensitive models.\u003c\/p\u003e\n\u003ch2\u003e\u003cstrong\u003eParallel op-amp architecture\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eFourteen OPA1612A audio operational amplifiers work in a parallel noise-reduction architecture. The design supports a measured SNR of up to 132dB and THD+N as low as 0.00006% at 1kHz and 32Ω, helping maintain low noise and distortion across the signal path.\u003c\/p\u003e\n\u003ch2\u003e\u003cstrong\u003eThree gain levels\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eLow, middle, and high gain settings let you match the amplifier to a broad range of headphones. Balanced gain ranges from -5.5dB to 19.6dB, while unbalanced gain ranges from -11.5dB to 13.6dB. Low gain is suited to sensitive IEMs, while the middle and high settings provide additional voltage gain for full-size headphones with impedances up to 600Ω.\u003c\/p\u003e\n\u003ch2\u003e\u003cstrong\u003eGallium nitride power supply\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eA custom low-noise gallium nitride power supply provides efficient power conversion with reduced switching noise. Its fast transient response is designed to supply current quickly during demanding passages while generating less heat during extended operation.\u003c\/p\u003e\n\u003ch2\u003e\u003cstrong\u003eBalanced and unbalanced connections\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eThe front panel provides a 4.4mm balanced headphone output, a balanced XLR headphone connection, and a 6.35mm unbalanced headphone output. Rear-panel connectivity includes XLR balanced inputs, RCA inputs, XLR pre-outputs, and RCA pre-outputs, allowing the H400 MK2 to work as both a headphone amplifier and a volume-controlled preamp.\u003c\/p\u003e\n\u003ch2\u003e\u003cstrong\u003eRelay-controlled volume\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eVolume is controlled by relay, supporting precise level adjustment for headphone and preamp use. The front control knob is paired with a clear IPS color display that keeps volume and operating information visible at a glance.\u003c\/p\u003e\n\u003ch2\u003e\u003cstrong\u003eCompact aluminum chassis\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eThe CNC-machined aluminum alloy enclosure measures approximately 10.0 x 1.89 x 7.44 inches (254 x 48 x 189 mm), keeping the H400 MK2 compact enough for a desktop system. The metal chassis also provides structural rigidity, heat dissipation, and electromagnetic shielding for the internal circuitry. Black and silver finishes are available.\u003c\/p\u003e\n\u003ch2\u003e\u003cstrong\u003eProtection circuitry\u003c\/strong\u003e\u003c\/h2\u003e\n\u003cp\u003eIntegrated DC, over-voltage, and overload protection monitors the amplifier during operation. These protection systems are designed to respond to abnormal electrical conditions and help protect both the connected headphones and the amplifier.\u003c\/p\u003e\n\u003ch3\u003e\u003cstrong\u003eProduct highlights\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eFully-balanced discrete headphone amplifier architecture\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003e14 OPA1612A operational amplifiers\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eCustom low-noise gallium nitride power supply\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eThree selectable gain levels\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eUp to 18W x 2 balanced output power into 16Ω\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eSNR up to 132dB\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eTHD+N as low as 0.00006% at 1kHz and 32Ω\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003e4.4mm, XLR balanced, and 6.35mm headphone outputs\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eXLR and RCA analog inputs\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eBalanced XLR and unbalanced RCA pre-outputs\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eRelay-controlled volume\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eFull-lamination IPS color display\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eCNC-machined aluminum alloy chassis\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eDC, over-voltage, and overload protection\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eSpecs\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eInputs: XLR balanced, RCA unbalanced\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eHeadphone outputs: 4.4mm balanced, XLR balanced, 6.35mm unbalanced\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003ePre-outputs: XLR balanced, RCA unbalanced\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eBalanced output power at 16Ω: 18W x 2\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eBalanced output power at 32Ω: 9W x 2\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eBalanced output power at 300Ω: 1100mW x 2\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eBalanced output power at 600Ω: 550mW x 2\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eUnbalanced output power at 16Ω: 5W x 2\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eUnbalanced output power at 32Ω: 2.5W x 2\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eUnbalanced output power at 300Ω: 260mW x 2\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eUnbalanced output power at 600Ω: 130mW x 2\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eSNR: 132dB\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eDynamic range: 132dB\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eTHD+N: -123dB, 0.00006% at 1kHz and 32Ω\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eInput impedance: 47kΩ\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eAmplifier output impedance: Near 0Ω\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eBalanced pre-output impedance: 44Ω\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eUnbalanced pre-output impedance: 22Ω\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eFrequency response: 20Hz to 100kHz, -0.5dB\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eBalanced gain: Low -5.5dB, middle 6dB, high 19.6dB\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eUnbalanced gain: Low -11.5dB, middle 0dB, high 13.6dB\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003ePower consumption: Less than 100W\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eAC input: 100V to 240VAC\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eDimensions: 10.0 x 1.89 x 7.44 inches (254 x 48 x 189 mm), W x H x D\u003cbr\u003e\n\u003c\/li\u003e\n\u003cli\u003eWeight: 4.85 lb (2.2 kg)\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003e\u003cstrong\u003eWhat’s included\u003c\/strong\u003e\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eSMSL H400 MK2 headphone amplifier\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"SMSL","offers":[{"title":"Default Title","offer_id":48209805377772,"sku":"APS-1415-1","price":539.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0225\/2721\/3642\/files\/3_eb850d71-b32d-4e1a-9830-103c4aa18671.png?v=1787328799","url":"https:\/\/apos.audio\/products\/smsl-h400-mk2-headphone-amplifier","provider":"Apos","version":"1.0","type":"link"}