In USB Audio, the Host (computer) and Device (DAC/Headphones) use independent oscillators, making perfect clock sync difficult. To avoid Buffer Overflow or Underflow (which causes audio glitches), the USB spec defines three Synchronization Types:   1. Synchronous Mode: Standard for basic USB audio devices How it works: The device's clock is locked to the USB bus. It adjusts its sampling rate to match the host's transmission speed. Pros: Simple design and low cost. Cons: Highly susceptible to USB bus jitter, resulting in mediocre sound quality. 2.  Asynchronous Mode : the standard for high-end audio (Hi-Fi DACs) How it works: The device uses its own high-precision clock and dictates the data rate to the host via a "Feedback Endpoint." Pros: Eliminates USB host jitter for the purest sound. Cons: Higher hardware cost and complex firmware development. 3. Adaptive Mode: A middle-ground solution How it works: The device adapts to the host’s data stream. It uses a VCXO (Voltage-Controlled Crystal Oscillator) to dynamically adjust its internal sampling rate to match the host. Pros: More stable than Synchronous mode; no feedback mechanism required. Cons: Still limited by host clock quality; more complex circuit design than Synchronous.   Comparison  Synchronous Adaptive Asynchronous Sync Mechanism Locked to USB Bus (SOF Signal) Internal (Follows Host Rate) Internal (Independent High-Precision Clock) Control by Host-Driven Device Passively Adapts to Host Rate Device-Driven (via Feedback Control) Jitter Highest (Strongly affected by USB Bus) Medium (Affected by Host Clock) Lowest (Determined by Device Hardware) Audio Performance Poor (Prone to noise floor or harshness) Fair to Good Superior (Hi-Fi Standard) Hardware Requirements Extremely Low Moderate (Requires clock adjusting circuitry) High (Requires Precision Clock and Independent Oscillators) Firmware Complexity Simple Moderate Complex (Requires Feedback Mechanism)  Applications Budget Toys, Telephony Headsets Legacy Sound Cards, General Computer Peripherals High-End DACs, Professional Recording Interfaces C-Media IC Sync Mode Comparison   Sync Mode Application Representative IC   Asynchronous High-Fidelity (Hi-Fi), Gaming, and Hi-Res Products CM6635, CM6542 Adaptive Entry-Level & Standard Universal Products CM108B, HS-100B Synchronous Legacy or Specialized Industrial Applications NA

USB Audio is a mature and standard digital audio interface for the major consumer products to transfer Music and Sound. The PC/NB with Windows, Mac, Linux operating system, Mobile phone with Android and iOS. They all support USB Audio. Even with the Gaming Console, PS4/PS5, Xbox 360/One, Switch, the USB Audio works as well. So, the USB Audio almost becomes the major peripheral audio interface. USB Audio has its standard spec. Now, the latest release standard is UAC 3.0 which is focus on Type C and power saving device. The major USB Audio Products on the market, for example USB Headset, USB Microphone, Docking, they are UAC1.0 and UAC 2.0. It is because UAC1.0 and UAC2.0 with the best compatibility for all the existing platforms.

C-Media's latest Environmental Noise Cancellation technology greatly improves the quality of your voice by cancelling out background noise, such as internet café gaming noise, Karaoke music and more. This means caller hear only clear, natural voice via C-media's Environmental Noise Cancellation. It provides you a better quality of communication!