Asynchronous USB Explained

Digital audio isn’t just about the data – 0s and 1s – and ensuring that each sample value is accurately converted into a corresponding output voltage. Also vital to achieving the highest fidelity is ensuring that each successive sample is reproduced at a precise time interval from those around it. If that time interval varies – an effect known as jitter – then the output waveform will be distorted. To prevent this, the master clock that controls the process should, ideally, be placed right next to the digital to analogue converter circuitry, not remote from it. Asynchronous mode USB provides for this because it allows data to be ‘pulled’ from the source as required, whereas in other modes the data is ‘pushed’ down the interface under control of the far inferior and distant clock in the computer.

World class headphone amplifier

The single-ended Class-A headphone amplifier of the DAC-V1 cleverly uses the pre-amp output amplifier for headphone drive. The moment headphones are plugged in, the output current drive is automatically turned up five times to give dynamic drive for all headphone impedances. The amplifier runs from a high voltage power supply so has the ability to drive high impedance headphones with the voltage swing they require for open and dynamic sound. The result is the audio stages are kept as simple and pure as possible for both normal and headphone modes.