SMSL H400 MK2 Fully Balanced Headphone Amplifier & Pre-amplifier

Ultimate Flagship Series SMSL H400 MK2 Fully Balanced Headphone Amplifier & Pre-amplifier An uncompromised, reference-grade desktop headphone amplifier and analog balanced pre-amplifier. Engineered with 14x OPA1612A op-amps, patented PLFC+ circuitry, and an ultra-low-noise GaN power supply to deliver ultimate drive power and class-leading measurements. Highlights at a Glance Colossal 18W Balanced Output Unleashes massive current drive (18W @ 16Ω, 9W @ 32Ω) to easily master power-hungry planar magnetic and dynamic headphones. Flagship Relay Volume Control Advanced electronic relay step attenuator guarantees perfect left-right channel matching, even at whisper-quiet levels. Premium GaN Power Supply Built-in custom low-noise Gallium Nitride (GaN) supply block isolates electrical noise for a clean, black background. Grounding Control Switch Rear toggle switch lets you choose between Grounded and Floating to instantly solve ground loop noise from your PC. Patented PLFC+ Balanced Amplification with 14x OPA1612A Op-Amps The core architecture of the SMSL H400 MK2 fully balanced headphone amplifier utilizes a fully balanced 4-channel patented headset amplifier circuit, PLFC+. Working in flawless harmony with an array of 14 high-end OPA1612A operational amplifiers, this flagship device achieves a breathtakingly low distortion rate (THD+N) of just 0.00006% and an outstanding signal-to-noise ratio of 132dB. High-precision, low-temperature drift resistors ensure stable, uncolored thermal performance over long listening sessions, bringing the nuances of high-resolution audio recordings directly to your ears with absolute fidelity. Colossal Power Output & Specialized Low-Gain IEM Tuning As a robust flagship headphone amplifier, the SMSL H400 MK2 provides unmatched headroom to power demanding full-sized planar magnetic and dynamic headphones, driving up to a monumental 18W at 16 ohms and 9W at 32 ohms over balanced connections. Simultaneously, sensitive in-ear monitors (IEMs) benefit from the low-gain setting (-11.5dB unbalanced / -5.5dB balanced), specifically tuned to suppress background noise. Backed by an electronic relay volume control system, it completely eliminates analog channel imbalance, offering solid, stable stereo imaging even at whisper-quiet listening volumes. Reference Balanced Pre-amplifier with Grounding Control The SMSL H400 MK2 easily transitions from an individual head-amp to a high-end balanced analog pre-amplifier. Featuring both balanced XLR and unbalanced RCA pre-outputs on the rear panel, it integrates with active studio monitors and external power amplifiers. Using the full-function RC-8D remote control, you can comfortably switch inputs and adjust volume levels from a distance. The rear-panel Grounding control switch (Floating/Grounded) allows you to break ground loops instantly when connected to computers or active monitors, while the internal high-quality muting relay system safeguards your downstream audio equipment by eliminating physical turn-on and turn-off pop sounds. In the Box Every SMSL H400 MK2 package includes the following essential components to ensure an immediate, high-fidelity connection to your audio system: SMSL H400 MK2 Full-Function Remote Control (RC-8D) AC Power Supply Cord (Matched to destination country) User Manual / Instruction Guide Frequently Asked Questions Can the SMSL H400 MK2 be used as a standalone pre-amplifier? Yes, the H400 MK2 functions as a high-fidelity analog pre-amplifier. It features XLR balanced and RCA unbalanced pre-outputs on the rear panel, allowing direct connection to active studio monitors or power amplifiers. You can easily toggle between headphone output and pre-out modes via the front panel, the remote control's FN button, or the menu. What does the Grounding Control (Floating/Grounded) switch do? When connecting a USB DAC to a PC and then outputting to an amplifier, ground loop noise (hum or static) can often occur. The Grounding control switch on the rear panel of the H400 MK2 allows you to switch between "Grounded" and "Floating" to break the ground loop electrically and achieve a completely quiet, silent background. Will sensitive in-ear monitors (IEMs) experience background noise or hiss? No. The SMSL H400 MK2 features a highly optimized low-gain setting (-11.5dB on single-ended / -5.5dB on balanced outputs) specifically designed for highly sensitive IEMs. This attenuates the noise floor, ensuring a completely quiet, hiss-free background. SMSL H400 MK2 Specifications Parameter Details Inputs Balanced (XLR), Unbalanced (RCA) Headphone Outputs 4.4mm Balanced, XLR Balanced, 6.35mm Unbalanced Pre-outputs XLR Balanced, RCA Unbalanced Output Power (Balanced) 16Ω: 18W 32Ω: 9W 300Ω: 1100mW 600Ω: 550mW Output Power (Unbalanced) 16Ω: 5W 32Ω: 2.5W 300Ω: 260mW 600Ω: 130mW SNR & Dynamic Range 132dB THD+N -123dB, 0.00006% (1kHz, 32 Ω) Input Impedance 47kΩ Headphone Amp Output Impedance Near 0 Ω Pre-output Impedance Balanced: 44Ω | Unbalanced: 22Ω Frequency Response 20Hz - 100kHz (-0.5dB) Gain Settings Balanced: Low (-5.5dB), Middle (6dB), High (19.6dB) Unbalanced: Low (-11.5dB), Middle (0dB), High (13.6dB) Power Consumption <100W (EN60065) Dimensions & Weight 254 x 48 x 189 mm (WxHxD) | 2.2kg (4.85lbs) Product Lineage Masterclass SMSL Balanced Amplifier Lineup Matrix With the legacy H300 and original H400 retired, the newly launched flagship SMSL H400 MK2 stands as our active ultimate powerhouse—combining monumental balanced power, advanced GaN power delivery, and surgical ground loop isolation. Why the Flagship H400 MK2 Leads the Lineup Monumental 18W Output Delivers a colossal 18W RMS @ 16Ω (and 9W @ 32Ω) of balanced drive, far outperforming the mid-tier H200 or original H400. Ground Loop Isolation Incorporates a professional rear-panel Grounding switch (Floating/Grounded) to isolate USB/PC ground loops and eliminate static. Bespoke GaN Power Equipped with a highly custom, low-noise Gallium Nitride (GaN) power supply, offering unprecedented power density and black background. SMSL Balanced Amplifier Lineup Matrix Spec / Feature SMSL H400 MK2 (Active Flagship) SMSL H200 (Active Mid-tier) SMSL H400 (Retired Legacy) Retail Price $549 (Active) $399 (Active) $510 (Retired) Production Status Active Flagship Active & Supported Discontinued Volume Architecture Precision Relays Precision Relays Precision Relays User Interface Color IPS Screen Color IPS Screen Color IPS Screen Grounding Control Switch Yes (Floating / Grounded) No No Balanced Power (16Ω) 18.0W + 18.0W RMS 4.0W + 4.0W RMS 15.0W + 15.0W RMS Balanced Power (32Ω) 9.0W + 9.0W RMS 5.0W + 5.0W RMS 7.5W + 7.5W RMS Balanced Power (300Ω) 1100mW + 1100mW RMS 1000mW + 1000mW RMS 1000mW + 1000mW RMS SNR / Dynamic Range 132dB 131dB 133dB THD+N 0.00006% (-123dB) 0.00007% (-122dB) 0.00006% (-123dB) Gain Steps (Balanced) Low (-5.5dB) / Mid (6dB) / High (19.6dB) Low (-3.5dB) / Mid (6dB) / High (19.7dB) Low (-5.8dB) / Mid (6dB) / High (20.4dB) Pre-outputs (Rear) XLR Balanced / RCA Unbalanced XLR Balanced / RCA Unbalanced XLR Balanced / RCA Unbalanced Width (Chassis size) 254mm (Full Size) 200mm (Ultra-Compact) 254mm Weight 2.20 kg / 4.85 lbs 1.20 kg / 2.65 lbs 2.03 kg / 4.47 lbs Power Consumption <100W (EN60065) <60W (EN60065) <50W (EN60065)