Audiophile glossary

Last updated September 2026

Plain-English definitions of the terms that come up when you start caring about digital audio quality on a Mac. Each entry is short and self-contained.

Bit-perfect

Playback where the digital samples in your file reach the DAC completely unaltered — no resampling, no mixing, no OS volume scaling. On macOS it requires exclusive mode plus a matching device sample rate. Full guide.

Exclusive mode (hog mode)

When a player takes sole control of an output device, bypassing the shared macOS Core Audio mixer. This is the key step for bit-perfect output, since the mixer otherwise resamples and mixes all audio. How to enable it.

Integer mode

Sending audio to the DAC as integer samples instead of converting to floating point first. It removes one processing step and, with exclusive mode and rate matching, keeps playback bit-perfect.

PCM (Pulse-Code Modulation)

The standard way digital audio is stored: amplitude sampled many times per second at a fixed bit depth. WAV, AIFF, FLAC and ALAC all decode to PCM.

DSD (Direct Stream Digital)

A 1-bit audio format sampled at very high rates — DSD64 (2.8 MHz) up to DSD512 (22.6 MHz) — used on SACDs and hi-res downloads. It encodes sound differently from PCM. Playing DSD on Mac.

DoP (DSD over PCM)

A method of sending a DSD bitstream to a DAC inside a PCM container, so a compatible DAC receives the original DSD untouched without a proprietary driver. The standard way to play DSD on macOS.

FLAC vs ALAC

Both are lossless codecs that compress PCM with no quality loss and decode to bit-identical audio — they sound the same. FLAC has wider support; ALAC is native to Apple software. FLAC vs DSD vs ALAC.

Sample rate & bit depth

Sample rate is how many times per second audio is measured (44.1 kHz on CD, up to 192 kHz+ for hi-res). Bit depth is the precision of each sample (16-bit on CD, 24-bit for hi-res). For bit-perfect output the DAC must run at the file’s native sample rate.

DAC (Digital-to-Analog Converter)

The component that turns digital audio into the analog signal your headphones or speakers play. An external DAC unlocks exclusive mode, integer mode and DSD playback on a Mac.

Gapless playback

Sample-accurate transitions between tracks with no silence inserted — essential for live albums, DJ mixes and classical works. Gapless on Mac.

ReplayGain

A standard that stores a track’s or album’s loudness in its tags so a player can normalize volume across your library without re-encoding the audio.

Upsampling

Converting audio to a higher sample rate (e.g. 44.1 kHz to 176.4 kHz) before output. It doesn’t add detail that wasn’t recorded, but some listeners prefer how a DAC handles a higher rate.

Signal path

The chain every sample travels from file to DAC. A signal-path indicator shows each stage and confirms whether the output is truly bit-perfect or whether something (resampling, volume, DSP) altered it.

Cue sheet

A plain text file describing where each track starts and ends inside one long audio file — the standard way a CD or a live set was ripped as a single image. A player that reads cue sheets shows the album as tracks you can skip and seek within; one that does not shows a single 74-minute file. Nothing about the audio differs; it is entirely a question of whether the player bothers.

Dither

A very small amount of deliberately shaped noise added when reducing bit depth — 24-bit to 16-bit, say. Without it the rounding error correlates with the signal and becomes audible distortion on quiet passages; with it, the error becomes a faint, benign hiss instead. Dither is only correct at the moment of a depth reduction. Applied to a file that is not being reduced it adds noise for nothing, which is why it belongs off by default.

Headroom and clipping

Digital audio has a hard ceiling at full scale. Boost a band by +9 dB and any sample already near that ceiling has nowhere to go: it clips, which is audible and ugly. Headroom management solves it by adding up the worst boost the chain could ask for and attenuating by exactly that much before the chain runs — you lose a little level and never clip.

Dynamic range (DR)

The distance between the quiet parts of a recording and the loud ones. A DR figure per track — the Pleasurize Music Foundation measure is the common one — tells you how heavily a master was compressed. It says nothing about whether a file is hi-res and everything about whether the mastering left the music room to breathe, which is usually the real difference when two releases of the same album sound unalike.

LUFS and EBU R128

A loudness measurement weighted the way hearing is, so two tracks matched by LUFS actually sound equally loud — which matching peak level does not achieve. ReplayGain 2.0 uses it at a −18 LUFS reference. It is why a well-implemented volume-levelling feature does not audibly change the music: it moves the level, not the content.

Nyquist frequency

Half the sample rate — the highest frequency a given rate can represent. A 44.1 kHz file reaches 22.05 kHz, comfortably past hearing. It is also how a quality report spots an upsampled file: a 24-bit/192 kHz file containing nothing above 22 kHz was made from a CD rip, whatever the tag says. See lossless vs hi-res.

Impulse response and convolution

An impulse response is a recording of how a room, a speaker or a filter reacts to a single instantaneous click — the fingerprint of everything that happens to sound in that space. Convolution applies that fingerprint, or its inverse, to music in real time. It is how room correction works: measure the room with REW, export the correcting filter, and the player convolves every sample with it.

Parametric EQ and Q

A parametric band has three controls rather than one: centre frequency, gain, and Q — how wide the affected band is around that centre. A high Q is a narrow surgical notch, useful against a room mode; a low Q is a broad tilt. A graphic equaliser is the same idea with frequency and Q fixed for you. See headphone EQ on a Mac.

Crossfeed

On speakers your left ear hears some of the right channel, slightly later and duller. Headphones remove that entirely, which is why a hard-panned sixties mix can feel like it is happening inside your skull. Crossfeed bleeds a delayed, filtered share of each channel into the other to put the image back outside your head. It is a deliberate colouration, and a useful one.

Aggregate device

A virtual audio device macOS assembles from several real ones so an application can play to all of them at once. Because it belongs to the system rather than to your player, an aggregate cannot be taken in exclusive mode — which is why playing to two DACs at once while staying bit-perfect needs a player that builds a private aggregate of its own.

See your signal path — free for 30 days

30 days, every feature, no account and no card.
$99.95 once if you keep it · macOS 15+ · Apple Silicon