2025 has turned into the year of the DAC and headphone amplifier, with manufacturers pushing harder on features, formats, and actual output power. Our latest DAC/Amp Editors’ Choice list made that clear, and SMSL is stepping into the same arena with the new DL400. It enters a category already crowded with strong options from FiiO, Topping, JDS Labs, Schiit Audio, Rotel, and Burson, so the details matter more than the marketing gloss.
The $499 DL400 is a black-only unit built around ESS’s ES9039MSPRO DAC, the XMOS XU-316 USB processor, and support for PCM up to 32-bit/768 kHz and native DSD512. SMSL claims MQA and MQA-CD decoding, which raises an eyebrow in 2025 considering the uncertainty around long-term MQA support. It will be worth confirming how committed SMSL is to maintaining that functionality through firmware updates.
Clocking is managed by an ultra-low phase-noise design intended to minimize jitter, and the fully balanced headphone amplifier relies on four Precision Linear Feedback Circuit modules and 11 premium dual op-amps. Output power is rated at 6W per channel at 16 ohms, 3W per channel at 32 ohms, and 700 mW per channel at 300 ohms—a relevant number for listeners running higher-impedance Sennheisers and similar designs. Two headphone jacks are provided: 4.4mm balanced and 6.35mm single-ended.
For tuning flexibility, the DL400 includes 8 PCM filter types and 9 “sound color” options. All inputs except Bluetooth support DSD, with coaxial, optical, and AES/EBU handling DoP64. Bluetooth 5.1 (Qualcomm) supports LDAC 24/96 and aptX HD, but not aptX Lossless or Bluetooth LE at this stage. The rear panel adds SMSL’s reversible I2S/XLR professional interface, allowing compatibility with multiple pinout standards.
For a category that keeps evolving, the DL400 looks like another technically ambitious entry. Now we wait to see how it performs against a field that has grown more competitive than ever.
SMSL DL400: Key Specifications
- Digital Inputs: USB, Optical, Coaxial, AES/EBU, Bluetooth 5.1, I2S (reversible I2S/XLR interface)
- Analog Outputs: RCA, XLR, 6.35mm headphone, 4.4mm balanced headphone
- DAC & Formats: ESS ES9039MSPRO; PCM 44.1–768 kHz (32-bit) and DSD 2.8–22.5 MHz (1-bit) via USB/I2S; Optical/Coax/AES to 192 kHz/24-bit; DoP256 (USB) and DoP64 (Optical/Coax/AES)
- MQA Support: MQA and MQA-CD decoding via USB, Optical, Coaxial, AES/EBU (notable given MQA’s uncertain future)
- Bluetooth: Qualcomm 5.1 with LDAC, aptX, aptX HD, AAC, SBC (no aptX Lossless or Bluetooth LE)
- Headphone Power: 6W ×2 @ 16Ω, 3W ×2 @ 32Ω, 700 mW ×2 @ 300Ω
- Amp Architecture: Fully balanced design, 4 PLFC modules, 11 premium dual op-amps, output impedance near 0Ω
- Gain: +9.5 dB unbalanced, +15.5 dB balanced
- Measured Performance:
- THD+N 0.00005% (line out) / 0.00009% (HPA)
- Dynamic Range 133 dB (XLR) / 127 dB (HPA)
- SNR 133 dB (XLR) / 127 dB (HPA)
- Filters & Tuning: 8 PCM filters and 9 sound “color” modes
- USB/OS Support: Asynchronous USB; Windows 7–11 (driver), macOS 10.6+ and Linux (driverless)
- Power Use: <40W operating, <0.5W standby
- Size & Weight: 250 × 47 × 240 mm (1.74 kg / 3.84 lbs)
The Bottom Line
The SMSL DL400 enters a crowded DAC/headphone amp field with a feature stack that actually stands out: ESS’s ES9039MSPRO DAC, the XMOS XU-316 USB engine, a fully balanced amplifier architecture with 11 dual op-amps, and real power—6 watts into 16 ohms and 700 mW into 300 ohms—enough to handle everything from sensitive IEMs to high-impedance classics. The reversible I2S/XLR interface gives it professional flexibility you rarely see at $499 USD, and the combination of 8 PCM filters, 9 sound-color modes, and wide DSD/PCM support lets users fine-tune the DL400 far beyond the usual SMSL template.
LDAC and aptX HD are onboard, though the lack of aptX Lossless and Bluetooth LE is worth noting. MQA and MQA-CD decoding are listed, but how meaningful that is in 2025 remains an open question. Still, with strong measured performance, a clean analog stage, and serious output capability, the DL400 has enough distinctive engineering to make it a compelling desktop centerpiece in a year full of heavy competition.
Where to buy: $499 at Amazon | S.M.S.L.
Related Reading:
- Best DAC/Amps For Headphones: Editors’ Choice
- FiiO K17 DAC/Amplifier Review: The Desktop Tank That Wants To Retire Your Dongles (And Maybe Your Amp, Too)
- Burson Audio Conductor GT4 Review: Desktop DAC/Amp Muscle With Audiophile Finesse
- FiiO K15 DAC Headphone Amp: The Affordable Desktop Option Schiit Hopes You Ignore
