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Unboxing new audio gear often ends with a confusing question: which cable goes where? The good news is that there are only a handful of connection types, and each has a clear job. Once you know them, you can wire up almost any system with confidence.
Analogue vs digital connections
Every audio cable carries one of two kinds of signal:
A continuous electrical wave
The signal is a voltage that mirrors the sound wave. Used between a DAC, turntable or preamp and an amplifier, and from amplifiers to speakers.
Numbers sent as pulses
The audio is still data (ones and zeros). It must reach a DAC before you can hear it. Used from TVs, computers, CD transports and streamers.
The key rule: a digital output must connect to a digital input, and an analogue output to an analogue input. Plugging the wrong ones together simply won’t work.
Line-level analogue connections
RCA (phono) cables
The classic red-and-white (right and left) plugs found on almost every home hi-fi component. They carry an unbalanced line-level signal between sources (CD player, streamer, DAC) and an amplifier. A turntable also uses RCA plugs, but must go to a PHONO input unless it has a built-in preamp.
3.5 mm (mini-jack)
The familiar headphone plug on phones, laptops and portable players. It’s also used as an AUX input on many speakers. A 3.5 mm-to-RCA cable connects a phone or computer to a stereo amplifier.
6.35 mm (¼-inch) jack
The larger jack used on studio headphones, guitars and pro equipment. Many headphones come with a screw-on or push-on adapter between 3.5 mm and 6.35 mm.
XLR and TRS (balanced)
XLR plugs have three pins and a locking latch; TRS is a 6.35 mm jack with an extra ring. Both carry a balanced signal: two copies of the audio, one inverted, so interference picked up along the cable cancels out. That’s why studios, live sound and long cable runs use balanced connections. Microphones almost always use XLR.
Balanced connections only bring their noise benefit when both devices have balanced inputs and outputs. An XLR-to-RCA adapter cable works, but the connection is then unbalanced.
Digital audio connections
| Connection | Looks like | Typical use | Notes |
|---|---|---|---|
| Optical (TOSLINK) | Square plug with a red light | TV, game console, CD player → soundbar, DAC, receiver | Immune to electrical hum. Remove the protective cap; don’t bend the cable sharply. |
| Coaxial (S/PDIF) | Single RCA plug, often orange | CD transport, streamer → DAC | Use a 75 Ω digital cable rather than a random analogue RCA lead for best reliability. |
| USB | USB-A, USB-B or USB-C | Computer or phone → DAC, audio interface | Supports hi-res audio. The standard connection for desktop and studio gear. |
| HDMI ARC / eARC | HDMI port labelled ARC or eARC | TV → soundbar or AV receiver | eARC carries lossless surround and Dolby Atmos; ARC is more limited. Also allows one remote to control volume. |
| AES/EBU | XLR plug | Pro and high-end digital gear | Balanced digital; looks like a mic cable but is designed for digital (110 Ω). |
Speaker wire and connectors
Passive speakers connect to an amplifier with two-conductor speaker wire. One conductor is marked (a stripe, ridge or coloured insulation) so you can keep track of polarity: amplifier + to speaker +, and – to –. If one speaker is wired the other way round, the bass sounds thin and the stereo image becomes vague.
Bare wire
Strip about 1 cm of insulation, twist the strands tightly and clamp them in the binding posts. Make sure no stray strand touches the other terminal.
Banana plugs
Push straight into the hole in the binding posts. Neat, secure and easy to reconnect.
Spade connectors
U-shaped forks that clamp under the binding post nut. Very firm contact.
Spring clips
Push-to-open clips on budget amps and speakers. Accept bare wire or pins only.
What gauge do I need?
Thicker wire (lower AWG number) has less resistance, which matters for long runs and low-impedance speakers. As a rule of thumb:
| Cable length (per speaker) | 8 Ω speakers | 4 Ω speakers |
|---|---|---|
| Up to 5 m (16 ft) | 16 AWG (1.5 mm²) | 16 AWG (1.5 mm²) |
| 5–10 m (16–33 ft) | 16 AWG (1.5 mm²) | 14 AWG (2.5 mm²) |
| Over 10 m (33 ft) | 14 AWG (2.5 mm²) | 12 AWG (4 mm²) |
Keep left and right cables the same length where practical, but don’t worry about small differences.
Subwoofer connections
- LFE / SUB OUT (RCA): the standard way to connect a sub to an AV receiver or an amplifier with a subwoofer output. Use a single RCA cable to the sub’s LFE or LINE input.
- Speaker-level (high-level) inputs: if your stereo amp has no sub output, many subwoofers can take a signal from the amp’s speaker terminals.
- Wireless: soundbars and some subs pair wirelessly with a transmitter.
Wireless connections
Cables aren’t always needed. Bluetooth is universal and easy for phones, but usually lossy. Wi-Fi streaming (AirPlay, Google Cast, Spotify Connect, multi-room platforms) can deliver lossless quality and doesn’t depend on your phone staying nearby. See our DACs & streaming guide for details.
How much should cables cost?
Buy well-made cables with solid connectors, appropriate length and correct specification (75 Ω for coaxial digital, a sensible gauge for speakers, certified high-speed cables for HDMI eARC). Beyond that, very expensive cables are rarely the most effective upgrade. Speakers, placement and the room make a much bigger difference.
Switch off (or turn the volume right down on) your amplifier before connecting or disconnecting speaker cables. A short circuit between + and – can damage the amplifier.
Frequently asked questions
Optical or HDMI ARC for my soundbar?
Use HDMI eARC/ARC if both devices support it — it carries more surround formats and lets your TV remote control the volume. Optical is a reliable backup and works with almost everything.
Can I use any RCA cable for a subwoofer?
Yes, a normal RCA cable works. A cable designed for subwoofers is often better shielded and may be easier to find in long lengths.
Do digital cables affect sound quality?
A working digital cable delivers the same data. Problems show up as dropouts, clicks or no sound at all, not as subtle tonal changes. Choose a cable built to the right specification and length.
What is bi-wiring?
Some speakers have two pairs of terminals (for bass and treble). Bi-wiring uses two separate cables to the amp. If you don’t bi-wire, leave the metal jumper links between the terminals in place.