The headphone jack is gone. In its place, a massive industry of USB dongles and portable players has emerged. Two giants dominate this microscopic battlefield: AKM and Cirrus Logic.

Modern audio engineering has shifted. Extreme fidelity no longer requires massive desktop boxes. It now lives inside silicon wafers smaller than a fingernail. This report breaks down the architectural differences between the most common chips found in your portable gear: the AKM AK4377, the Cirrus Logic CS43131, and the flagship CS43198.

AKM AK4377: The Velvet Sound

The AKM AK4377 is the workhorse of entry-to-mid-tier portable audio. You find this chip in wireless receivers and compact USB-C adapters. Its primary claim to fame is the “Velvet Sound” architecture. This isn’t just marketing jargon; it refers to a specific tuning philosophy.

Unlike older resistor-ladder designs, the AK4377 uses a 32-bit Delta-Sigma modulator. Its secret weapon is the Class G headphone amplifier. Most amps burn battery by keeping voltage high all the time. Class G switches rails dynamically. If the music is quiet, it drops the voltage. If a drum hits, it spikes the voltage. This saves massive amounts of battery life.

The sound? Listeners describe it as “musical.” The distortion profile leans toward even-order harmonics. These align with musical octaves, creating a sensation of warmth. It is forgiving. Badly recorded tracks sound acceptable here.

Cirrus Logic CS43131: Analytical Precision

If AKM is about warmth, Cirrus Logic is about the truth. The CS43131 comes from their MasterHIFI line. The goal here is absolute transparency.

This chip pushes the noise floor down to -115 dB. It uses proprietary mismatch shaping to randomize silicon errors, turning distortion into white noise that gets pushed into ultrasonic frequencies where you cannot hear it.

It also features “Impedance Fingerprinting.” When you plug in headphones, the chip measures the resistance. Sensitive in-ear monitors get a low-gain, low-noise signal. Hard-to-drive studio headphones get the full 2 Volts RMS. It happens instantly.

Digital Filters: The Hidden EQ

A DAC must convert 0s and 1s into a continuous wave. To do this, it uses a reconstruction filter. This filter removes “imaging artifacts”—ghost signals that appear at high frequencies. How the manufacturer implements this filter changes the sound.

The Power Equation

Audiophiles often ignore battery life, but mobile users cannot. The difference in power draw between these chips is massive. A Dual DAC setup sounds better but drains your phone twice as fast.

Spec Showdown

Use the filters below to isolate specific performance tiers.

The Dual DAC Advantage

You often see devices marketed as “Dual DAC.” This is not snake oil. When you use two chips (like two CS43198s), you can run them in Mono Mode. One chip handles the left channel; the other handles the right.

This physically isolates the channels. Crosstalk vanishes. The soundstage widens because the left signal can no longer bleed into the right signal via the power rail. Furthermore, summing the signals mathematically lowers the noise floor by 3 decibels.

The “Hump” Issue: Early Cirrus implementations had a flaw known as the “Cirrus Hump.” A specific distortion spike occurred at -12 dBFS volume. This was caused by the power-saving Dynamic Range Enhancement (DRE) switching rails too aggressively. Modern firmware fixes this by moving the switch point to -44 dBFS, making the transition inaudible.

The Jitter War: Clocking

A DAC is only as good as its timing. If the samples are converted at slightly irregular intervals, you get “jitter,” which manifests as a subtle blurring of high frequencies.

Asynchronous Mode: Both AKM and Cirrus chips now operate almost exclusively in Asynchronous USB mode. They do not rely on the noisy clock signal from your phone or computer. Instead, they use local crystal oscillators (often from NDK or Accusilicon) located millimeters from the DAC chip.

High-end implementations of the CS43198 often use dual femtosecond clocks—one for 44.1kHz multiples (music) and one for 48kHz multiples (movies)—to ensure mathematically perfect timing.

DSD: Direct vs. Converted

Direct Stream Digital (DSD) is a niche format favored by purists. The handling of DSD differs radically between architectures.

Thermal Dynamics in 2026

Physics dictates that high fidelity requires energy, and energy creates heat. The shift to “Dongle DACs” has created a thermal bottleneck.

The CS43198, particularly in Dual configuration, pushes the thermal envelope of small aluminum enclosures. Unlike the AK4377 which runs cool, high-end Cirrus implementations can reach surface temperatures of 40°C during DSD playback. This heat triggers “Thermal Throttling,” where the chip intentionally lowers its internal clock speed, introducing jitter to protect the silicon.

Buying Advice: If you live in a hot climate or keep your dongle in a pocket, the single-chip CS43131 or AK4377 is safer. They rarely throttle. Reserve Dual CS43198 units for desktop use where airflow is available.

Headphone Power Calculator

Will these chips actually drive your headphones? Enter your headphone specs below to see if you need a CS43131 (Standard) or a Dual CS43198 (High Power).

The Creative X4 Mystery

A side note on marketing: The Sound Blaster X4 claims to use a “CS43918.” This chip does not exist in public catalogs. The specs (114 dB SNR) are lower than the flagship CS43198 (130 dB). It is likely a custom variant or a typo for legacy silicon; proof that model numbers do not always tell the whole story.