Formats explained.
Digital audio formats and file types - FLAC, DSD, PCM, MP3, sample rates and bit depths, lossless vs lossy, and the Hi-Res Audio certification.
0-9
2-way vs 3-way speakers
A 2-way speaker splits the audio between two drivers: woofer (bass + midrange) and tweeter (highs). A 3-way adds a dedicated midrange driver…
24-bit / 96 kHz (hi-res sample rate + bit depth notation)
"24-bit / 96 kHz" is the shorthand notation for a hi-res audio file: 24 bits per sample (144 dB dynamic range) at 96,000 samples per second …
3.5mm Jack (mini-jack)
The 3.5mm jack (also called mini-jack, 1/8-inch, aux) is the most common consumer audio connector - used for headphones, phones, and line-le…
48V Power Supply (for TPA3255 amps)
The 48V power supply is the rail voltage that lets TPA3255 amplifiers reach their full rated power. Most budget TPA3255 amps ship with a sma…
5.1 / 7.1 surround sound configurations
5.1 and 7.1 are speaker configurations for surround sound. 5.1 = 5 main speakers (front L/R + center + rear L/R) + 1 subwoofer. 7.1 adds two…
A
AAC codec
AAC (Advanced Audio Coding) is a lossy audio codec best known as the default Bluetooth codec on Apple devices. Quality is very good at 256 k…
Active vs Passive Speakers
Active speakers have built-in amplifiers - just add a source. Passive speakers need an external amp. Active is simpler; passive gives more u…
AirPlay 2
AirPlay 2 is Apple's wireless audio streaming protocol built into iPhone, iPad, Mac, and Apple TV. Supports lossless streaming to compatible…
AKM AK4493SEQ
The AKM AK4493SEQ is a premium 32-bit Delta-Sigma DAC chip from Asahi Kasei Microdevices. Audiophiles often describe AKM chips as sonically …
aptX Adaptive
aptX Adaptive is Qualcomm's newest Bluetooth codec. Variable bitrate (279-420 kbps) automatically adjusts based on wireless signal quality. …
aptX-HD
aptX-HD is Qualcomm's hi-res Bluetooth audio codec that transmits up to 576 kbps at 24-bit / 48 kHz. It's the second-best Bluetooth audio qu…
B
Balanced XLR
Balanced XLR is a professional audio connection that uses 3 wires (signal+, signal-, ground) instead of the 2 used by RCA. Balanced connecti…
Bass Reflex Port
A bass reflex port (or "port") is a tuned tube in a speaker cabinet that extends low-frequency response by using rear-radiating driver energ…
Bi-amping
Bi-amping uses two separate amplifier channels per speaker - one for the woofer, one for the tweeter. Requires speakers with removable jumpe…
Bit Depth (16-bit vs 24-bit)
Bit depth determines the dynamic range of a digital audio signal. 16-bit (CD quality) has 96 dB dynamic range. 24-bit (hi-res) has 144 dB - …
Bluetooth 5.x (5.0/5.1/5.2/5.3/5.4)
Bluetooth 5.0-5.4 are the current-generation wireless audio standards. Each revision improves range, energy efficiency, and codec support. B…
Bookshelf vs Tower Speakers
Bookshelf speakers are compact 2-way designs meant for stand or shelf placement. Tower speakers are large floor-standing 3-way designs. Book…
C
Chromecast Audio (Google Cast)
Google Cast (formerly Chromecast Audio) is Google's wireless audio streaming protocol. Casts from Android, Chrome browser, and cast-enabled …
Class-A amplifier
Class-A is the traditional analog amplifier topology where transistors conduct continuously. Legendary for smoothness and lack of crossover …
Class-AB amplifier
Class-AB is the traditional linear amplifier topology in vintage receivers and most non-Class-D integrateds. Roughly 50% efficient, warm sou…
Class-D amplifier
Class-D is a switching amplifier topology that turns transistors fully on and off at very high frequency, rather than partially conducting l…
Coaxial S/PDIF
Coaxial S/PDIF is a digital audio connection using a single 75-ohm RCA cable. Carries the same digital signal as optical Toslink but is more…
Crossover (speaker)
A crossover is the internal electrical filter that splits an incoming audio signal into frequency bands for each driver (woofer, midrange, t…
D
DAC / Amp Combo
A DAC/amp combo is a single unit combining a digital-to-analog converter with an amplifier — either a headphone amp (for headphones) or a sp…
Damping Factor
Damping factor is the ratio of speaker impedance to amp output impedance. Higher damping factor means the amp controls the speaker cone bett…
Delta-Sigma DAC
Delta-Sigma (ΔΣ) is the dominant modern DAC architecture. It uses massive oversampling and noise shaping to achieve extremely low distortion…
DLNA / UPnP
DLNA and UPnP are open protocols for streaming media over a home network. Older than modern proprietary protocols (AirPlay, Chromecast) but …
Dolby Atmos
Dolby Atmos is a spatial audio format that adds height channels to traditional surround sound. In stereo hi-fi, "Atmos music" is downmixed t…
DSD (Direct Stream Digital)
DSD (Direct Stream Digital) is a 1-bit high-sample-rate digital audio format used on SACD discs. DSD64 samples at 2.8 MHz; DSD256 at 11.3 MH…
E
Enclosure (speaker cabinet)
A speaker enclosure (cabinet) is the box that houses drivers. Cabinet material, bracing, and internal volume dramatically affect sound. Well…
EQ (Equalizer) – Parametric vs Graphic
A parametric EQ adjusts frequency, gain, and Q-factor (bandwidth) per band - very precise. A graphic EQ has fixed frequency bands with only …
ES9038Q2M
The ESS Technology ES9038Q2M is one of the most popular budget-audiophile DAC chips. It delivers reference-tier measurements (THD+N below -1…
Ethernet audio streaming
Wired Ethernet is the most reliable way to feed a network streamer. No Wi-Fi dropouts, no interference, unlimited bandwidth for hi-res strea…
F
FiiO K-series (K11, K13, K17)
FiiO's K-series is a line of desktop DAC/headphone amp combos targeting budget-to-mid audiophile buyers. K11 (~$130) uses a CS43198 DAC; K13…
FLAC (Free Lossless Audio Codec)
FLAC is the dominant lossless audio compression format. Compresses audio to about 60% of original size with zero quality loss - decodes back…
Fosi Audio (brand)
Fosi Audio is a Chinese hi-fi brand founded in 2015 that helped kick off the modern budget-audiophile Class-D revolution. Known for the V3 m…
Frequency Response
Frequency response describes how a component reproduces different frequencies of the audible range (typically 20 Hz - 20 kHz). Flat frequenc…
G
Gain (input gain)
Gain is how much an amplifier boosts the input signal in volts. Higher gain means smaller input signals reach the same output loudness. Mism…
GaN (Gallium Nitride) power supply
GaN (Gallium Nitride) is a semiconductor material used in modern switching power supplies. GaN transistors switch faster than silicon, resul…
Google Cast for Audio
Google Cast for Audio is the underlying protocol behind Chromecast Audio - lets you stream audio from Android apps to compatible speakers ov…
Ground loop hum
A ground loop is an audible 60 Hz (US) or 50 Hz (EU) hum caused by multiple grounded devices creating a current loop through ground wires. F…
H
HDMI ARC (older standard)
HDMI ARC (Audio Return Channel) is the older HDMI audio-back standard - carries compressed Dolby Digital / DTS 5.1 but NOT lossless Atmos. S…
HDMI eARC
HDMI eARC (Enhanced Audio Return Channel) sends hi-res audio from your TV back to an amplifier or soundbar via the same HDMI cable that deli…
Headphone amp (dedicated)
A dedicated headphone amp is designed specifically to drive headphones with clean voltage/current. Better than phone/laptop outputs for dema…
Headphone impedance
Headphone impedance ranges from 16Ω (portable-friendly) to 600Ω (studio reference). Higher-impedance headphones need more voltage from the a…
Hi-Res Audio certification
The Hi-Res Audio logo (from JAS/Japan Audio Society) certifies gear capable of reproducing 24-bit / 96 kHz or higher audio. A useful indicat…
I
I2S (Inter-IC Sound)
I2S is the internal digital audio bus used between chips (typically between a USB receiver chip and DAC chip). Some premium DACs expose I2S …
IEM (In-Ear Monitor)
An IEM (In-Ear Monitor) is a headphone that seals inside the ear canal - originally designed for stage musicians. Extremely portable, excell…
Impedance matching
Impedance matching ensures your amp and speakers (or amp and headphones) work together efficiently. Speaker amp: check the amp handles your …
Isodynamic Ribbon Tweeter
An isodynamic ribbon tweeter is a planar-magnetic-style high-frequency driver used in premium bookshelf speakers. Ribbon tweeters deliver ex…
J
JAS Hi-Res Audio certification
JAS (Japan Audio Society) is the standards body behind the Hi-Res Audio gold logo. Products must meet minimum specs: 40 kHz+ frequency respo…
JBL Studio Series (bookshelves)
JBL Studio Series is JBL's consumer hi-fi speaker line. Studio 530 (bookshelf) and Studio 590 (tower) are popular budget audiophile picks wi…
Jitter
Jitter is timing error in digital audio - tiny variations in when each sample is played. Excessive jitter causes subtle distortion and reduc…
JRiver Media Center
JRiver Media Center is a paid music library and playback software popular in the audiophile community. Handles massive libraries, native DSD…
K
KEF LS-series speakers
KEF LS50 Meta and LS Wireless are premium reference bookshelf speakers using KEF's Uni-Q coaxial driver (tweeter inside midrange). LS50 Meta…
Kernel streaming / WASAPI (Windows)
WASAPI (Windows Audio Session API) is Windows' bit-perfect audio path that bypasses the Windows mixer, avoiding sample rate conversion and v…
Klipsch Reference Premiere series
Klipsch Reference Premiere (RP) is Klipsch's mainstream hi-fi speaker line - horn-loaded compression tweeters, high sensitivity (95+ dB), wa…
Koss KPH series headphones
The Koss KPH series (KPH30i, KPH40, KPH30 Wireless) are cult-favorite budget on-ear headphones from Koss. Retro Walkman-era styling, excepti…
L
LDAC
LDAC is Sony's hi-res Bluetooth audio codec that transmits up to 990 kbps (about 3x the bit rate of standard Bluetooth). It preserves near-C…
Line-level output
Line-level output is the standard consumer audio signal level - about 2 Vrms peak from RCA jacks, ~4 Vrms from balanced XLR. This is the lev…
Lossless vs Lossy audio
Lossless formats (FLAC, ALAC, WAV) preserve every original bit; decode identical to source. Lossy formats (MP3, AAC, Ogg) discard "less-audi…
Low-pass filter (LPF)
A low-pass filter (LPF) passes frequencies below a cutoff and attenuates frequencies above. Used in subwoofer crossovers to keep only bass, …
M
Midrange driver
A midrange driver is the speaker driver dedicated to reproducing the middle frequency range (typically 300 Hz - 4 kHz). Used in 3-way and la…
Monoblock amplifier
A monoblock amp contains one amplifier channel per chassis - you need two for stereo. Advantages: no crosstalk, dedicated power supply per c…
MQA (Master Quality Authenticated)
MQA is a proprietary "folded" hi-res audio format designed for streaming. Claims lossless-equivalent quality in smaller files by unfolding c…
Multipoint Bluetooth
Multipoint Bluetooth lets a device (headphones, speaker) connect to two source devices simultaneously - typically phone + laptop. Switches a…
N
NAS (Network Attached Storage) for audio
A NAS is a network-connected storage device that holds your FLAC/DSD music library accessible to any network audio streamer. Popular in the …
NCore / Hypex (premium Class-D modules)
Hypex NCore is a premium Class-D amplifier module used in high-end audiophile amps (Mola Mola, Bel Canto, some Marantz). Reference-tier Clas…
Near-field vs Far-field listening
Near-field listening = speakers within 3-6 feet, sitting between them (studio monitor style). Far-field = speakers 6-15 feet away, room acou…
Noise floor
Noise floor is the level of background noise (hiss, hum) present in an audio system when no signal is playing. Lower noise floor = better dy…
O
Op-amp (operational amplifier)
An op-amp is a general-purpose analog gain stage used inside DACs, preamps, and headphone amps. In hi-fi, op-amp rolling (swapping the chip …
Open-back vs Closed-back headphones
Open-back headphones have perforated ear cups - air moves freely, giving wider soundstage but no isolation (leaks in AND out). Closed-back c…
Optical (Toslink) connection
Toslink (Optical S/PDIF) is a digital audio connection using a fiber-optic cable with square-end connectors. Immune to electrical interferen…
Oversampling (in DACs)
Oversampling is a technique where a DAC processes audio at a multiple of the original sample rate (e.g., 8x, 32x). Allows gentler analog fil…
P
PCM (Pulse-Code Modulation)
PCM is the standard digital audio encoding used by CDs (44.1 kHz / 16-bit), most streaming services (up to 24-bit / 192 kHz), and computer a…
PFFB (Post-Filter Feedback)
PFFB (Post-Filter Feedback) is a circuit technique that dramatically reduces distortion in Class-D amps under real-world speaker loads. Amps…
Phono stage / phono preamp
A phono stage (or phono preamp) is a specialized preamp that boosts the very low-level signal from a turntable's cartridge (~5 mV) up to lin…
Planar Magnetic driver
Planar magnetic is a headphone driver technology using a thin conductive diaphragm suspended between two rows of magnets. Faster transient r…
Power output (watts explained)
Amplifier power (in watts) determines maximum SPL from a given speaker. But specs vary widely by measurement condition (impedance, distortio…
Preamp vs Amp vs Integrated
A preamp handles input switching, volume control, and signal buffering. A power amp does the heavy lifting to drive speakers. An integrated …
Q
Q-factor (in EQ and speakers)
Q-factor describes the sharpness/bandwidth of a resonance or filter. In parametric EQ, high Q = narrow surgical cut/boost; low Q = wide gent…
Qobuz
Qobuz is a French hi-res music streaming service - competitor to Tidal and Apple Music Lossless. Streams FLAC hi-res (up to 24-bit / 192 kHz…
QoS (Quality of Service) for network audio
QoS (Quality of Service) is a router feature that prioritizes network traffic. Enabling QoS for your audio streamer prevents dropouts caused…
Quad-DAC configuration
A quad-DAC design uses four DAC chips (or channels) in parallel per stereo pair - two per channel. Increases dynamic range, reduces noise fl…
R
R2R Ladder DAC
R2R (Resistor-Resistor ladder) is a discrete DAC architecture that converts digital audio to analog using an array of precision resistors. A…
RCA (unbalanced) connection
RCA is the classic red-and-white unbalanced analog audio connector. Universal in consumer hi-fi. Simple, cheap, but susceptible to interfere…
Rear-firing port (speaker)
A rear-firing port is a bass reflex port located on the back of the speaker cabinet. Common on bookshelves. Needs 4-8 inches of space behind…
Room correction / DSP
Room correction is DSP (digital signal processing) that measures your listening room's acoustic problems and applies corrective EQ. Fixes ba…
Roon Ready
Roon Ready certification means a streamer/DAC properly implements the Roon protocol (RAAT - Roon Advanced Audio Transport). Roon subscribers…
S
Sample rate (kHz)
Sample rate is how many audio samples are captured per second, measured in kHz. 44.1 kHz = CD; 48 kHz = video/DVD; 96 kHz and 192 kHz = hi-r…
SBC (Bluetooth codec)
SBC (Subband Coding) is the mandatory baseline Bluetooth audio codec - every Bluetooth device supports it. Sound quality is mediocre (~192-3…
Silk Dome Tweeter
A silk dome tweeter is the most common high-frequency driver in budget and mid-tier bookshelf speakers. Silk's natural damping produces a sm…
Speaker Impedance (4Ω vs 8Ω)
Speaker impedance is the electrical resistance a speaker presents to the amplifier, measured in ohms (Ω). Typical values are 4Ω, 6Ω, or 8Ω. …
Speaker Sensitivity
Speaker sensitivity is a measure of how loud a speaker plays given a fixed amount of amplifier power (expressed as dB/W/m). A 90 dB sensitiv…
Spotify Connect
Spotify Connect is Spotify's wireless streaming protocol - lets you cast from the Spotify app to compatible speakers over Wi-Fi. Streams up …
Streamer (network audio player)
A streamer is a dedicated network audio player that connects to your amp/DAC/receiver and pulls music from streaming services and network dr…
Subwoofer crossover
The subwoofer crossover splits your audio signal - sends low frequencies (typically below 80 Hz) to the sub, and everything above to your ma…
T
THD+N (Total Harmonic Distortion + Noise)
THD+N (Total Harmonic Distortion + Noise) measures how much a piece of audio equipment alters or adds to the original signal. Lower is bette…
TIDAL Connect
TIDAL Connect is Tidal's wireless streaming protocol - same concept as Spotify Connect. Casts hi-res FLAC from the Tidal app to compatible r…
Tone controls (bass/treble)
Tone controls are simple bass and treble adjustment knobs (or remote buttons) on integrated amps. Purist audiophiles disable them for "flat"…
TPA3255
The TPA3255 is a Texas Instruments Class-D amplifier chip that has become the de facto standard for budget audiophile amps since 2020. It de…
Tweeter (dome vs ribbon)
A tweeter is the small driver that reproduces high frequencies (typically 2 kHz - 20+ kHz). Common types: silk dome (smooth, budget), alumin…
U
UAC2 (USB Audio Class 2)
UAC2 is the USB Audio Class 2 standard - the driver-free protocol that lets modern USB DACs work with any operating system without vendor dr…
Unbalanced vs Balanced connections
Unbalanced (RCA) uses 2 wires per channel: signal + ground. Balanced (XLR, TRS) uses 3 wires: signal+, signal-, ground - noise picked up on …
Upsampling
Upsampling is the process of converting audio from a lower sample rate to a higher one before DAC conversion (e.g., 44.1 kHz to 384 kHz). Ha…
USB-C DAC connection
USB-C DAC is a direct digital audio connection from a computer, phone, or tablet to a DAC using a USB-C cable. Modern DACs achieve bit-perfe…
V
Vinyl playback (turntable chain)
Vinyl playback requires: turntable + cartridge + phono preamp + amp/receiver + speakers. Signal path: cartridge (~5 mV) into phono stage (bo…
Voltage rail (in amp power supplies)
Voltage rail is the DC voltage supplied to an amplifier's output stage from its power supply. Higher voltage rail = more maximum power outpu…
Volume control (digital vs analog)
Analog volume controls (potentiometers) attenuate the analog signal after amplification - can add channel imbalance at low volumes. Digital …
VU meter
A VU (Volume Unit) meter is a slow-responding audio level indicator originally from the analog broadcast/recording era. Modern digital "VU m…
W
Watts explained (amplifier power)
Watts (W) measure power output. But watts don't translate 1:1 to loudness - doubling watts adds only 3 dB (barely audibly louder). 100W amp …
Wi-Fi 6 audio streaming
Wi-Fi 6 (802.11ax) is the current Wi-Fi standard with better congestion handling, lower latency, and more concurrent devices than older Wi-F…
WiiM ecosystem (Mini, Pro, Ultra, Amp)
WiiM makes affordable Wi-Fi/Ethernet music streamers popular in the budget audiophile community. Mini (~$100), Pro (~$150), Ultra (~$350 wit…
Woofer
A woofer is the largest driver in a speaker cabinet - handles bass and low midrange frequencies. Common sizes in bookshelves: 4-6.5 inches; …
X
X-over (crossover) simplified
"X-over" is shorthand for "crossover" - the filter that splits an audio signal into frequency bands for different drivers (woofer vs tweeter…
Xbar / patchbay (analog routing)
A patchbay (sometimes called "xbar" for cross-bar) is an audio routing panel with rows of jacks that let you flexibly connect sources to des…
XLR connector
XLR is the 3-pin round audio connector used for balanced analog signals - pro audio standard. Very robust locking mechanism. See "Balanced X…
XMOS USB audio chip
XMOS is a UK semiconductor company whose USB audio interface chips (XU208, XU216, XU316) are used inside most modern hi-res USB DACs. Handle…
Y
Y-cable / Y-splitter
A Y-cable (also called Y-splitter) has one input and two outputs (or vice versa). Common use: split a single output to feed two amps, or com…
Y-jack (2-in-1 headphone splitter)
A Y-jack for headphones is a small adapter that splits one 3.5mm output into two - lets two people share the same music source (phone, airpl…
Yamaha AV Receiver series
Yamaha AV Receivers (RX-V, RX-A, Aventage series) are among the most popular AVRs in home theater. Known for warm musical sound, YPAO room c…
YouTube Music audio quality
YouTube Music streams at up to 256 kbps AAC (Premium tier). Not lossless like Tidal or Apple Music Lossless. Free tier is only 128 kbps AAC …
Z
Z-height (soundstage depth)
Z-height refers to the perceived depth/front-to-back dimension of a stereo soundstage. Well-recorded music with good speaker placement gives…
Z-Reviews (audiophile YouTuber)
Z Reviews (ZeosPantera) is one of the longest-running audiophile YouTube reviewers - known for irreverent, no-nonsense reviews of Chi-Fi and…
Zeppelin / classic hi-fi speaker references
Certain classic speakers - B&W 801, Quad ESL, Wilson Watt Puppy, Klipsch La Scala, JBL 4344 - are "reference" designs that audiophiles compa…
Zone-2 (multi-room audio)
Zone-2 (or Zone-A/B) is a feature on some AV receivers and multi-room amps to send audio to a second listening area (patio, kitchen) - often…
