The DAC industry criticism surrounding filter design and chip specifications is gaining renewed attention after veteran engineer John Siau of Benchmark Media Systems outlined persistent technical flaws in modern digital-to-analog converters. His findings suggest that widely marketed DAC specifications may overlook measurable distortion issues that occur during real-world playback.
According to reporting by Headphonesty, the issue centers on intersample clipping and implementation design choices that are not reflected in conventional performance metrics.
Technical Specifications
Intersample clipping occurs when reconstructed analog waveforms exceed the maximum digital level of 0 dBFS (decibels relative to full scale), despite digital samples themselves remaining within limits. This happens because pulse-code modulation (PCM) audio captures discrete sample points, while actual waveform peaks can occur between those samples.
When DACs reconstruct the signal through interpolation, these “between-sample” peaks can exceed the limit by as much as 3.01 dB. Without sufficient headroom, this results in brief distortion bursts resembling white noise. Engineers note that these artifacts often manifest as subtle brightness rather than obvious clipping, making them difficult to detect without targeted analysis.
Benchmark’s internal testing, cited in the report, found over 1,100 intersample overs in a five-minute track, indicating the issue can occur multiple times per second in typical music playback.
Industry Context
The findings challenge common assumptions within the hi-fi sector, where DAC chip selection—particularly between manufacturers such as ESS and AKM—is often treated as a primary determinant of sound quality.
Siau argues that this focus is misplaced. Technical documentation from Benchmark indicates that roughly 90% of a DAC’s performance is determined by its analog circuitry, including current-to-voltage (I/V) conversion, power supply regulation, and component matching.
This means two devices using the same DAC chip can exhibit significantly different measurable and audible performance depending on their implementation. The report suggests that marketing emphasis on chip specifications may obscure more critical engineering factors.
■ Related News
Filter Design and Signal Integrity
Digital filter modes—such as minimum phase, slow roll-off, and no oversampling (NOS)—are frequently promoted as offering distinct sonic characteristics. However, the analysis raises concerns about their accuracy.
NOS designs, in particular, remove digital filtering to eliminate pre-ringing artifacts. Engineers note that this approach introduces aliasing, a form of distortion where high-frequency components fold back into the audible range. This can alter transient timing and waveform accuracy.
Testing cited in the report shows that linear-phase filters maintain waveform consistency across multiple conversion stages, while alternative filters introduce cumulative deviations. These findings suggest that some filter options may prioritize subjective coloration over signal fidelity.
Market Positioning
The report also highlights a disconnect between measurable performance and published specifications. Conventional metrics such as signal-to-noise ratio (SNR) may not account for intersample distortion, even at levels exceeding 130 dB.
To address the issue, Benchmark incorporates approximately 3.5 dB of digital headroom in its DAC designs. This allows reconstructed peaks to pass without clipping but reduces measurable output levels slightly—an adjustment that may appear unfavorable on spec sheets despite improving real-world accuracy.
Streaming Standards and Industry Response
While DAC manufacturers have not broadly adopted headroom-focused designs, streaming platforms have moved in a similar direction. Services including Spotify, Apple Music, and YouTube recommend maintaining true peak levels below -1 dBTP (decibels true peak) to avoid intersample clipping during playback.
Engineers suggest that reducing playback volume by even 3 dB can mitigate the issue in consumer setups, offering a practical workaround in the absence of hardware-level solutions.
Industry Reaction
The broader implication is a reassessment of how DAC performance is communicated and evaluated. The emphasis on chip branding and selectable filters may not fully represent real-world audio behavior, particularly under modern mastering practices that push signals close to digital limits.
As high-resolution streaming and lossless formats continue to expand, the report indicates that implementation details—rather than headline specifications—are likely to play a larger role in determining playback accuracy.
