In 2026, high-resolution audio isn’t a luxury reserved for studio engineers and obsessive audiophiles—it’s the baseline expectation for anyone who takes their music seriously. With streaming services now offering 24-bit/192kHz catalogs as standard and DSD256 libraries expanding exponentially, the weak link in your playback chain isn’t your headphones or speakers anymore. It’s the anemic headphone jack on your laptop or the compromised audio circuitry in your smartphone. This is where the USB DAC (Digital-to-Analog Converter) transforms from optional upgrade to essential infrastructure.
But here’s the reality: not all USB DACs are created equal, and the market has fractured into dizzying specializations. A dongle that excels with your IEMs will choke driving planar magnetic headphones. A desktop powerhouse that anchors your home office might draw too much current for mobile use. And with USB4 becoming ubiquitous and AI-powered digital signal processing entering the mainstream, buying a DAC in 2026 means navigating technical specifications that didn’t exist three years ago. This guide cuts through the noise, giving you the expert framework to identify exactly what performance features matter for your specific listening ecosystem—whether you’re building a reference-grade desktop rig or seeking pocketable perfection for commutes.
What Is a USB DAC and Why Does High-Resolution Audio Demand One?
At its core, a USB DAC performs one critical job: converting the ones and zeros of digital audio files into the smooth, continuous voltage waveforms your headphones or speakers require. Your computer’s onboard audio chipset does this too, but it’s compromised by a electrically noisy environment, subpar components, and design priorities that favor cost over fidelity. High-resolution audio files—uncompressed FLAC, DSD, or MQA streams—contain vastly more temporal and dynamic information than CD-quality audio. Extracting that nuance demands precision clocking, ultra-low-noise power supplies, and sophisticated digital filtering that generic audio chips simply can’t deliver.
In 2026, the stakes have risen further. With 32-bit/768kHz PCM and DSD512 becoming accessible formats, the delta between basic conversion and true high-resolution playback has widened dramatically. A modern USB DAC doesn’t just decode these files; it reconstructs the analog signal with temporal accuracy measured in picoseconds, preserving the micro-dynamics and spatial cues that define the high-resolution experience. Without this dedicated hardware, you’re essentially paying for premium fuel and pouring it into an engine designed for regular.
The Technical Foundation: Bit Depth, Sample Rate, and File Formats Demystified
Before diving into DAC architectures, you need to understand what you’re asking them to decode. Bit depth determines dynamic range—the difference between the quietest and loudest sounds. Each additional bit adds roughly 6dB of range, so 16-bit CD audio offers 96dB, while 24-bit hi-res pushes this to 144dB. In 2026, 32-bit float processing has become common in professional workflows, though the audible benefits above 24-bit remain debated among engineers.
Sample rate defines how many times per second the analog waveform is measured. The 44.1kHz CD standard captures frequencies up to 22.05kHz—barely beyond human hearing. High-resolution audio pushes this to 96kHz, 192kHz, or even 768kHz, but the real benefit isn’t extended frequency response. It’s improved time domain accuracy and gentler filter requirements in the DAC itself. When evaluating specs, prioritize devices that handle your actual library. A DAC advertising DSD512 support means nothing if you only stream 24/96 FLAC. Focus on stable, low-jitter performance at your target sample rates rather than chasing theoretical maximums.
2026 State of the Art: How USB DAC Technology Has Evolved
The USB DAC landscape has matured dramatically. We’ve moved beyond the “chip wars” of the early 2020s, where a single DAC IC brand dominated conversations. Today’s designs integrate sophisticated FPGA (Field-Programmable Gate Array) processing, custom digital filters, and adaptive clocking systems that divorce performance from the DAC chip itself. USB4 integration has eliminated the bandwidth constraints that once plagued native DSD streaming, while Thunderbolt 4 ports on premium units offer direct memory access for theoretically lower latency.
Perhaps most significantly, power management has become a differentiator. With USB-C Power Delivery now delivering up to 100W, desktop-grade DAC/amp combos can run entirely from a laptop’s bus power without compromising amplifier headroom. Meanwhile, ultra-efficient designs for mobile use leverage ARM co-processors to handle complex decoding while sipping battery. The line between “portable” and “desktop” performance has blurred, but the implementation philosophies remain distinct—understanding this split is crucial for making the right investment.
Form Factor Deep Dive: Choosing Between Desktop, Portable, and Ultra-Portable Designs
Your usage scenario dictates everything else. Desktop USB DACs prioritize absolute performance, offering discrete linear power supplies, full-sized XLR outputs, and robust chassis that isolate internal components from interference. They’re designed for stationary listening with high-impedance headphones or powered monitors, and their larger footprints accommodate superior heat dissipation and circuit separation.
Portable DACs strike a balance, fitting in a jacket pocket while delivering enough clean power for most headphones up to 300 ohms. They typically feature built-in batteries to avoid draining your source device and to maintain stable voltage rails. In 2026, many include wireless charging coils and can double as power banks—a nod to the convergence of audio and mobile tech.
Ultra-portable dongle DACs have become surprisingly capable, thanks to efficient DAC ICs and advanced power management. These thumb-sized devices draw power directly from your phone or laptop, making them ideal for IEMs and efficient headphones. However, their limited current output and reliance on noisy bus power means they hit a performance ceiling with demanding loads. Choose form factor based on your primary listening location and headphone inventory—not the other way around.
The DAC Chipset Ecosystem: Understanding AKM, ESS, and Emerging Architectures
The DAC chip itself is just one ingredient in the recipe. That said, understanding the landscape helps decode marketing claims. AKM’s Velvet Sound architecture, revived after their 2020 factory fire, emphasizes natural timbre and low-level detail retrieval, with their latest 4499EX chip featuring programmable digital filters that manufacturers can tune to their house sound. ESS Sabre chips dominate the ultra-high-end, their HyperStream II modulation delivering vanishingly low THD+N figures, though some listeners find their presentation analytically sterile without careful analog stage design.
In 2026, we’re seeing a rise in custom R2R (resistor ladder) DACs implemented via FPGA, offering a fundamentally different approach to conversion that eschews delta-sigma modulation for a more direct, NOS (Non-Oversampling) philosophy. These designs appeal to listeners prioritizing tonal purity over spec-sheet dominance. Meanwhile, Cambridge’s proprietary CAP (Custom Audio Processing) chips and similar in-house designs from boutique manufacturers blur the line between chip maker and DAC brand. The takeaway? Judge the complete implementation, not just the silicon brand.
Beyond PCM: DSD, MQA, and Next-Generation Codec Support
Your DAC’s codec support must align with your content library. DSD (Direct Stream Digital) uses a single-bit, high-frequency approach fundamentally different from PCM’s multi-bit encoding. Native DSD decoding bypasses the DAC’s internal PCM conversion path, theoretically preserving the format’s purity. In 2026, most quality DACs support DSD256, with DSD512 available on premium models. However, the audible difference between DSD64 and higher rates remains contentious—prioritize clean DSD64 performance over shaky DSD512 support.
MQA (Master Quality Authenticated) has evolved into MQA-CD and MQA-Studio variants, though its controversial licensing model has spurred open-source alternatives like FLAC-192-HDR. Many 2026 DACs include MQA rendering (unfolding the final folds in hardware) rather than full decoding, relying on software for the initial unfold. If you stream Tidal or use other MQA sources, confirm whether the DAC performs full decoding or just rendering—this affects CPU load and theoretical fidelity. For the growing catalog of 24-bit/192kHz FLAC from Apple Music, Amazon, and Qobuz, pristine PCM performance remains paramount.
The Critical Headphone Amplifier Stage: Power, Impedance Matching, and Topology
A DAC is only half the equation; the amplifier stage determines whether that clean conversion reaches your ears intact. Output power, measured in milliwatts (mW) at a given impedance, tells you whether the amp can drive your headphones to adequate levels without clipping. Planar magnetic headphones like the Audeze LCD series might demand 1W+ at 32 ohms, while sensitive IEMs require microvolt-level noise floors to avoid hiss.
Impedance matching matters more than raw power. A 600-ohm Sennheiser HD 800S needs high voltage swing, while a 16-ohm Campfire Andromeda demands high current and low output impedance to avoid frequency response anomalies. In 2026, many DAC/amps feature adaptive output impedance that automatically adjusts based on connected load—a killer feature for hybrid collections.
Amplifier topology splits between Class AB (balanced efficiency and performance), Class A (pure, but power-hungry), and the emerging Class D designs leveraging GaN (Gallium Nitride) transistors for desktop power in portable form factors. For desktop setups, discrete transistor designs still reign supreme. For portable, well-implemented Class D offers shocking performance per milliwatt.
Connectivity Matrix: USB-C, USB4, Wireless, and Analog Integration
The physical connection defines your DAC’s versatility. USB-C has become the universal standard, but not all USB-C ports are equal. USB4 certification guarantees 40Gbps bandwidth and intelligent power negotiation, eliminating the compatibility issues that plagued early USB-C audio devices. Look for USB4 if you plan to run long cables or connect through hubs—its error correction preserves signal integrity where older USB implementations would degrade.
Beyond USB, consider your analog ecosystem. Fixed-line outputs to powered monitors demand different voltage levels (typically 2V RMS unbalanced, 4V RMS balanced) than variable headphone outs. Some 2026 DACs offer true preamp functionality with remote volume control and input switching, letting them anchor a complete desktop system. Digital inputs (coaxial, optical, AES/EBU) remain relevant for connecting CD transports or game consoles—don’t assume USB-only is future-proof.
Wireless connectivity has matured beyond gimmick status. Wi-Fi 7-enabled DACs can stream lossless audio directly from NAS drives or cloud services, bypassing your computer’s audio stack entirely. Bluetooth 5.4 with LC3plus and aptX Lossless offers near-wired quality for casual listening, but shouldn’t be your primary connection for critical hi-res playback.
Power Supply Purity: Why Clean Energy Matters More Than You Think
The adage “garbage in, garbage out” applies exponentially to power. A DAC’s analog stage is exquisitely sensitive to power supply noise—every millivolt of ripple translates directly to the output signal. Desktop DACs with internal linear power supplies and massive toroidal transformers deliver the cleanest juice, but at the cost of size and heat. Many audiophiles take this further with external linear power supplies (LPS), though the benefits plateau without addressing the USB power path itself.
Portable DACs face a steeper challenge. Battery power provides isolation from wall noise, but switching regulators needed for voltage conversion introduce their own high-frequency artifacts. Premium portable units now use multiple stages of low-noise LDO (Low-Dropout) regulators, with separate supplies for digital and analog sections. Some even feature supercapacitor banks that deliver instantaneous current during dynamic peaks, a trick borrowed from high-end automotive audio.
For USB-powered dongles, galvanic isolation is non-negotiable in 2026. This breaks the electrical connection between your computer’s noisy ground plane and the DAC’s sensitive circuits. Look for devices advertising 1000V+ isolation and independent crystal oscillators—these prevent your GPU’s activity from modulating your music’s background blackness.
Clocking Precision: Mastering Jitter and Time Domain Accuracy
Jitter—timing variations in the digital clock—smears transients and collapses soundstage depth. In 2026, asynchronous USB has become table stakes, where the DAC’s internal clock controls data flow rather than the computer’s imprecise clock. But not all asynchronous implementations are equal. The quality of the master clock oscillator itself, measured in parts per billion (ppb) of deviation, determines the ultimate resolution.
Femtosecond clocks, once exotic, now appear in mid-tier DACs. These oscillators reduce phase noise to levels where the limiting factor becomes the atomic jitter of the DAC chip itself. More important than the clock spec is how it’s implemented. DACs with FIFO (First In, First Out) buffers re-clock the data stream, completely decoupling input jitter from the conversion process. This is superior to simple PLL (Phase-Locked Loop) based re-clocking, which can track low-frequency jitter rather than eliminating it.
For the ultimate in precision, some flagship DACs now incorporate atomic clock references or GPS-disciplined oscillators. While overkill for most listeners, these technologies demonstrate how far the pursuit of temporal accuracy has come. Practical advice: prioritize DACs with dedicated oscillators for each sample rate family (44.1kHz, 48kHz) rather than a single clock with rate conversion.
Balanced vs. Single-Ended Outputs: Navigating the Great Debate
Balanced connections (XLR or 4.4mm Pentaconn) use two signal conductors per channel plus ground, with the receiving device subtracting the inverted signal from the positive. This common-mode rejection cancels noise picked up along the cable and eliminates ground loop issues. Theoretically, balanced offers 6dB more voltage swing and lower crosstalk. In practice, the benefits depend entirely on implementation.
A poorly executed balanced output—where the “inverted” signal is simply generated by an op-amp inverter—offers no real advantage over single-ended. True balanced designs feature completely separate DAC channels and amplifier circuits per phase, effectively doubling component count and cost. For short cable runs in a low-noise environment, quality single-ended (RCA or 3.5mm) can sound identical or even preferable if the balanced topology adds unnecessary complexity.
In 2026, the 4.4mm Pentaconn has largely replaced 2.5mm TRRS as the portable balanced standard, offering superior mechanical stability and current handling. For desktop setups, XLR remains king. If your headphones support balanced connections, prioritize DACs with true differential output stages rather than single-ended outputs with balanced adapters tacked on.
Digital Filter Algorithms: Shaping Sound Signature in the Digital Domain
Before conversion, every DAC must filter the digital signal to remove ultrasonic images. The choice of filter dramatically affects perceived sound—sharp “brick wall” filters preserve frequency response but introduce pre-ringing and time smearing. Slow roll-off filters preserve transient attack but can leak ultrasonic noise into the analog stage. This is where manufacturer expertise shines.
Most 2026 DACs offer multiple filter options, selectable via companion apps. Minimum phase filters eliminate pre-ringing at the expense of slightly relaxed imaging. NOS (Non-Oversampling) modes bypass digital filtering entirely, appealing to purists but requiring exceptional analog post-filtering. Some manufacturers now employ AI-trained filters that adapt to content genre, applying different algorithms for orchestral versus electronic music.
The key insight: filters are a legitimate tuning tool, not just marketing fluff. When auditioning DACs, cycle through the filter options with familiar tracks. The differences are often more audible than swapping cables. A DAC offering only a single, fixed filter is making choices for you—ensure those choices align with your sonic preferences.
Software Ecosystem: Drivers, Firmware, and Platform Compatibility in 2026
Hardware is only as good as its software stack. In 2026, class-compliant USB audio has improved, but ASIO (Windows) and Core Audio (macOS) still offer lower latency and exclusive mode access that bypasses OS mixer interference. Linux users should verify ALSA and PipeWire compatibility—some DACs require proprietary drivers for full feature access.
Firmware update frequency indicates manufacturer support. The best brands release quarterly updates that improve performance, add features, and patch compatibility issues. Check whether updates require Windows-only utilities or can be applied via mobile apps. With Apple’s shift to USB-C across all devices, iOS compatibility has become seamless, but Android remains fragmented. Look for DACs certified for Android’s “USB Audio Class 3.0” to ensure reliable sample rate switching and power management.
Companion apps have become central to the experience. Beyond filter selection, they control gain staging, channel balance, EQ, and even room correction when paired with measurement microphones. A clunky, crash-prone app undermines an otherwise excellent DAC. Before buying, download the app and read recent reviews—software quality is a leading indicator of long-term support.
Budget Realities: What Performance to Expect at Every Price Point
The price-to-performance curve has steepened. Below $100, dongle DACs deliver shocking value, often matching the measured performance of $500 units from five years ago. Expect clean output for efficient headphones, but limited power and basic feature sets. The $100-$300 range is the sweet spot for portable all-in-one units, offering true balanced outputs, MQA rendering, and battery power.
From $300-$700, desktop separates begin to outshine portables. You’ll find linear power supplies, superior amplifier stages, and FPGA-based processing. This tier delivers genuine endgame performance for most listeners—diminishing returns kick in hard above this point. The $700-$1500 range buys exotic topologies, custom R2R designs, and boutique components. Audible improvements exist but require resolving systems to appreciate.
Above $1500, you’re paying for craftsmanship, brand prestige, and the last 1% of measured performance. These flagship units often feature modular designs allowing future upgrades, justifying their cost for committed hobbyists. For 2026, consider this: a $400 DAC with a $600 headphone amplifier usually trounces a $1000 all-in-one unit. Allocate budget based on your weakest link, not arbitrary price tiers.
Mobile Integration: Android, iOS, and the Future of On-the-Go Hi-Fi
Smartphones have become legitimate high-resolution sources, but integration remains nuanced. iOS devices with USB-C (iPhone 15 and newer) offer plug-and-play simplicity with class-compliant DACs, automatically adjusting sample rates and delivering bit-perfect output. Android’s fragmentation means you must verify USB Audio Class support for your specific device—Samsung Galaxy and Google Pixel phones lead here, while budget Android devices often resample everything to 48kHz.
Power draw is critical for mobile use. A DAC pulling more than 500mA will rapidly deplete your phone’s battery and may trigger power management to throttle performance. Premium portable DACs now include “low power mode” that switches off the amplifier stage when using line-out, extending listening time. Some even feature passthrough charging, powering your phone while decoding audio.
In 2026, the rise of lossless streaming over 5G has made local file storage less critical, but offline libraries remain relevant for flights and remote listening. Consider DACs with microSD slots that function as standalone music players, bypassing your phone entirely. This “transport mode” eliminates RF interference and battery concerns while delivering pristine playback.
Setup and Optimization: Extracting Maximum Performance From Your DAC
Proper setup separates good sound from revelation. Start with cables—not because exotic cables improve sound, but because poorly shielded USB cables act as antennas for Wi-Fi and cellular interference. Use cables shorter than 2 meters with ferrite chokes for desktop setups. For portable use, keep the DAC physically separated from your phone’s antenna module.
Gain staging is crucial. Set your DAC’s hardware volume to 100% (or use fixed line-out) and control level at your amplifier or active speakers. This maximizes the DAC’s dynamic range. If using the DAC’s built-in headphone amp, start with low gain and switch to high gain only if you exceed 70% volume—high gain modes often increase distortion and noise.
Software configuration matters. On Windows, use ASIO or WASAPI exclusive mode to prevent system sounds from interrupting music and to avoid Windows’ internal resampling. On macOS, set the DAC as the system output and configure Audio MIDI Setup for your target sample rate before launching your player. Disable all OS-level “enhancements” and EQ—these apply destructive processing that undermines your DAC’s precision.
Finally, consider physical isolation. Desktop DACs benefit from vibration damping feet (micro-vibrations modulate clock crystals), while portable units should avoid direct contact with phone bodies. A simple silicone pad between phone and DAC can lower the noise floor audibly.
Troubleshooting Audio Anomalies: Diagnosing Common Problems
Even premium DACs can misbehave. Ground loop hum—typically a 50/60Hz buzz—indicates multiple ground paths. Break the loop by powering all devices from the same outlet, or use a USB isolator. If hum persists on balanced outputs, your DAC’s common-mode rejection ratio may be insufficient.
Crackling or dropouts usually trace to USB power instability or driver conflicts. Try a powered USB hub to provide clean 5V, or update chipset drivers. On Windows, disable USB selective suspend in power settings. If dropouts occur at specific sample rates, the DAC’s clock may be marginal—try forcing your player to resample to a stable rate like 96kHz.
Hiss with sensitive IEMs points to amplifier noise floor issues. Switch to low gain, enable IEMatch (impedance attenuation), or use the DAC’s line-out to a dedicated low-noise amp. If bass sounds thin or compressed, check your power supply—voltage sag under load starves the amplifier’s output stage, a common issue with underpowered USB ports.
Finally, if imaging feels flat or soundstage collapsed, suspect jitter. Try a shorter USB cable, connect directly to a motherboard port (avoid front-panel headers), or enable the DAC’s “jitter elimination” mode if available. Sometimes the simplest solution is a different USB port—some share bandwidth with other peripherals, introducing data timing errors.
Future-Proofing Your Investment: Trends Defining the Next Era
The USB DAC you buy today should remain relevant through 2030. Prioritize USB4 compatibility—even if you lack USB4 sources now, the specification’s intelligent power negotiation and error correction will become standard. Modular designs with replaceable amp cards or DSP modules offer genuine longevity, allowing you to upgrade as new headphone technologies emerge.
Software-defined radio (SDR) integration is an emerging trend, enabling DACs to receive broadcast audio directly from streaming services without computer intervention. While nascent in 2026, this could eliminate the computer from the chain entirely. Similarly, AI-powered room correction and hearing profile calibration are moving from DSP boxes into the DAC itself—ensure any model you consider has enough processing headroom for future firmware features.
Physical durability matters. The 4.4mm and USB-C connectors should be chassis-mounted, not PCB-mounted, to survive years of insertion cycles. Check for firmware update policies—brands committing to five years of support are effectively future-proofing your hardware against OS changes. Finally, consider resale value. Established brands with active communities hold value better, making that premium purchase less painful if you upgrade later.
Frequently Asked Questions
1. Will a USB DAC actually make my Spotify streams sound better?
Spotify’s maximum 320kbps OGG Vorbis is already audibly transparent to most listeners in casual testing. A USB DAC won’t magically reveal “hidden” detail in compressed streams. However, it will provide cleaner amplification, lower noise floor, and better channel separation than your laptop’s headphone jack, which can improve perceived clarity and reduce listening fatigue. The real transformation happens with lossless sources—Spotify’s rumored lossless tier in 2026 would be the ideal match.
2. What’s the minimum power output I need for my 250-ohm headphones?
For 250-ohm dynamic headphones like the Beyerdynamic DT 1990 Pro, target at least 200mW at 250 ohms to reach 110dB SPL peaks (orchestral crescendos). This translates to roughly 7V RMS output swing. Check the DAC’s specs at your headphone’s impedance, not just the headline 32-ohm rating. Planar magnetics at 250 ohms may need 500mW+ due to their current-hungry nature.
3. Is DSD512 support necessary, or is DSD256 enough?
DSD256 (11.2MHz) captures ultrasonic content well beyond any recording equipment’s capability. DSD512 offers theoretical benefits in noise shaping and filter design, but no peer-reviewed study has demonstrated audible superiority with real music. DSD256 is the practical ceiling for 2026—any DAC that handles it cleanly will satisfy even the most demanding listeners. Budget for better analog stage design over higher DSD rates.
4. Can I use a USB DAC with my gaming console or TV?
Yes, but with caveats. PlayStation 5 and Xbox Series X support USB audio output, but typically lock to 48kHz and apply system-level mixing that can degrade quality. For movies, many smart TVs output stereo PCM via USB-C or optical—connect your DAC to these for superior headphone audio. For true surround gaming, a DAC with HDMI input extraction is required, though these remain niche products in 2026.
5. Why does my DAC get hot, and should I be concerned?
Heat indicates power dissipation, primarily from the amplifier stage and voltage regulators. Desktop DACs running Class A output stages can reach 50-60°C at idle—this is normal and often designed for thermal stability. Portable DACs should stay below 40°C; excessive heat suggests inefficient design or insufficient heatsinking, which can shorten component lifespan. If your DAC thermally throttles (volume drops after extended use), contact support.
6. What’s the difference between a DAC and a DAC/amp combo?
A pure DAC provides only line-level outputs (RCA or XLR) and requires a separate headphone amplifier. A DAC/amp combo integrates both functions, offering direct headphone drive. In 2026, the performance gap has narrowed—many combo units rival separates up to the $1000 tier. Choose separates when you need specific amplifier characteristics (e.g., tube warmth) or plan to upgrade components independently. Combos win for simplicity and value.
7. How do I know if my USB port provides enough clean power?
Use a USB power meter to measure voltage under load—it should hold steady above 4.9V. Voltage sag below 4.8V indicates insufficient current capacity. For desktop DACs, connect to rear motherboard ports directly tied to the chipset. Avoid USB hubs unless they’re externally powered and certified for high-current devices. If in doubt, use a dedicated USB power injector or the DAC’s optional external power supply.
8. Are balanced cables worth the extra cost for short runs?
For runs under 1 meter in a low-RF environment, quality single-ended cables perform identically to balanced, assuming the DAC’s single-ended output is well-designed. Balanced shines in noisy environments (offices with fluorescent lights) or long cable runs to powered speakers. If your headphones are balanced and your DAC offers true differential output, use it—but don’t spend $200 on a balanced cable expecting night-and-day improvements at your desk.
9. Can a USB DAC improve audio production and mixing workflows?
Absolutely. A transparent DAC with flat frequency response and minimal distortion provides accurate monitoring, crucial for mixing decisions. Look for DACs with <0.0005% THD+N and linear phase filters. However, production also demands low-latency monitoring—ensure the DAC supports ASIO/Core Audio buffers below 128 samples. Some 2026 models include DSP for zero-latency foldback, bypassing the computer entirely for direct monitoring.
10. What’s the single most important spec to prioritize when buying blind?
Dynamic range (SNR) at your listening level. A DAC advertising 130dB SNR is meaningless if you listen at 80dB SPL—the relevant noise floor is what you hear, not the chip’s theoretical limit. Look for SINAD (Signal-to-Noise and Distortion) measurements at 50mV output for IEMs, or 2V RMS for full-sized headphones. Independent measurements from sites like Audio Science Review provide real-world performance data far more valuable than spec sheets. When in doubt, buy from manufacturers who publish full measurement sweeps, not just cherry-picked highlights.