Nyquist

Output hardware

What does a USB DAC change?

It gives the computer a separate digital audio device with its own supported formats, clock, conversion stage, and outputs. That is a technical change, not an automatic sound-quality guarantee.

Digital in, analog out

A digital-to-analog converter turns digital samples into the analog signal used by headphones, an amplifier, or powered speakers. Macs already contain conversion hardware for built-in outputs. A USB DAC provides another device whose supported sample rates, bit depths, channels, volume controls, and analog stage may differ.

Direct device selection on macOS

Nyquist can bind its playback engine to a specific CoreAudio output without changing the system-wide route. It remembers the device by stable identifier and falls back to the system default if the DAC is disconnected.

With sample-rate matching enabled, Nyquist asks the selected DAC for the source rate or a clean same-family multiple, waits for its clock to settle, and reports the resulting rate. If the device cannot accept an appropriate rate, the signal path reports the mismatch rather than claiming an unchanged path.

Exclusive mode and volume

Exclusive, or hog, mode asks macOS to give Nyquist sole ownership of the DAC while playback is active. This can prevent another app from changing the device configuration, but it also makes the device unavailable elsewhere. Volume may be controlled by the DAC hardware or by software gain, depending on the device.

DSD requires compatible hardware

On Mac, Nyquist can send DSF and DFF audio as DSD over PCM to a DAC that recognizes it. The required PCM frame rate rises with the DSD rate, so the DAC must advertise a compatible mode. A DAC that only accepts ordinary PCM cannot decode this transport.

iPhone and iPad differ

A compatible iPhone or iPad can use wired audio hardware, including some USB DACs, but iOS and iPadOS manage the route. Nyquist does not present the same direct CoreAudio device selection, exclusive mode, or local DSD path offered on macOS. Cable, adapter, power, and hardware support also matter.

A DAC is not automatically better

A USB DAC may expose outputs, rates, controls, or analog performance that suit a system. Whether that produces an audible improvement depends on the complete chain and the existing hardware. Nyquist reports the route and device behavior; it does not assign a quality score to the DAC.

Related: Nyquist USB DAC features, bit-perfect audio, and Bluetooth vs. USB audio.