Aux, RCA and Optical Audio Cables: Which One Fits Your Gear?

Posted by Console Mate on 25th Aug 2026

Aux, RCA and Optical Audio Cables: Which One Fits Your Gear?

Audio leads look interchangeable until the moment you need one. Three plugs do most of the work in an Australian lounge room — the small 3.5 mm jack, the round RCA phono plug, and the square optical Toslink — and they are not alternatives to each other. Buy the wrong one and it simply will not go in, or worse, it goes in and nothing comes out.

This guide covers the whole audio range: aux leads, extensions, splitters, RCA leads and adaptors, subwoofer feeds, digital coaxial and optical. Everything mentioned is stocked in Australia.

Measure the plug before you order

Nearly every wrong-lead return in this category comes down to plug size, so start here.

  • 3.5 mm is the small one — the headphone plug on a phone, a laptop or a TV. Stereo versions are TRS: two rings on the plug.
  • 6.35 mm (1/4 inch) is the large jack used by amplifiers, mixers, keyboards and studio headphones. It will not fit a phone, a laptop or a set of earbuds.
  • RCA (phono) is the round single plug, used in pairs for stereo — one for the left channel and one for the right.
  • Toslink is optical, and it is a square plug with a red light inside. Mini Toslink is the same size as a 3.5 mm headphone plug and often shares the headphone socket, which is why the two get confused.

And one that catches people out: digital coaxial is not optical. Digital coax uses a single RCA plug and carries the signal down copper; optical carries it down glass or plastic fibre. They do the same job and they are not interchangeable.

Phone, laptop or TV into speakers: the aux lead

If both ends are 3.5 mm sockets, you want a male-to-male stereo lead. The only real decision is length, so the range is a ladder: the 1.2 metre aux lead is the everyday length for a car or a desk, the 3 metre covers most rooms, the 5 metre is enough to cross a room or reach a wall-mounted TV, and the 10 metre lead runs from a desk to a hi-fi on the far wall.

If the socket is on the side or bottom of the device and a straight plug would be strained, the right-angle 1.5 m aux lead has one right-angle plug and one straight plug — the angled end turns through 90° so it sits flat.

When the aux lead will not reach

If you already own a lead that works, extend it rather than replacing it. An extension has a male plug at one end and a female socket at the other: the 1.8 m stereo extension adds 1.8 m, the 5 m extension adds five, which is enough to cross a room rather than just clear a desk.

To share one source between two sets of headphones, the 3.5 mm headphone splitter takes one 3.5 mm plug in and gives two stereo sockets out — phone, laptop, tablet, TV or console.

3.5 mm at one end, RCA at the other

This is the commonest mixed-connector job in the house: something with a headphone socket needs to reach something with phono inputs.

RCA to RCA: hi-fi, amp and speakers

For a straight stereo run between components, the 3 metre stereo RCA lead has RCA plugs at both ends, so the source does not have to sit next to the amplifier.

To make an existing RCA lead longer you have three choices, and which one you need depends on what is on the end of the cable you already own. The 1.2 m RCA extension and the 3 m RCA extension are plugs-to-sockets extensions — they plug onto your lead and give you another 1.2 or 3 metres. The gold-plated RCA coupler is a coupler with a socket at both ends, which is the piece that joins two leads end to end. And if you only need one channel — a subwoofer feed, for instance — the single-channel RCA extension is a single plug to a single socket rather than a stereo pair.

Splitting an RCA signal, and getting round a corner

Two splitters, and the difference is the gender:

  • The RCA splitter has one RCA plug in and two RCA sockets out — it goes into an output and feeds two leads.
  • The all-female RCA Y splitter is all female: one socket in and two sockets out, three sockets in total, so it sits between three leads that all end in plugs.

When a straight plug will not fit behind a cabinet, the RCA right-angle adaptor converts a straight RCA lead into a right-angle one, with an RCA male plug on one arm and a female socket on the other. It comes in black and red so a stereo pair stays colour-matched, and there are twin packs and 4 packs for doing both channels or a whole rack at once.

Subwoofers are mono

The subwoofer or LFE channel is a single channel, so one lead is all you need — you are not losing anything by not using a stereo pair. The single RCA cable 3 m is one RCA plug at each end on three metres of flexible, fully shielded coaxial cable, and it doubles as a digital coaxial or composite video lead.

If your amplifier has one sub output and the subwoofer has two inputs, the subwoofer Y splitter takes one male RCA in and gives two male RCA out — all three connectors are plugs, not sockets, which is the detail to check against your gear.

Digital coaxial: use a real 75Ω lead

Digital coaxial S/PDIF runs down a single RCA plug, but it is not the same as an analogue audio lead and a general-purpose RCA cable is not built for it. The 0.8 m and the 3 m digital coaxial cable are true 75Ω coaxial leads on RG6 quad-shielded cable, 6 mm outside diameter, with an oxygen-free copper centre and gold-plated RCA plugs.

Optical audio: Toslink and mini Toslink

Optical is the square plug. Four things go wrong with it, and there is a part for each:

  • The cable is too short. The Toslink coupler joins two optical cables end to end — a full-size Toslink socket at both ends.
  • The port is the small one. The Toslink to mini Toslink adaptor lets a standard full-size Toslink cable plug into a 3.5 mm mini optical port.
  • The cable sticks straight out. The Toslink right-angle adaptor turns the exit through 90° with a 360° swivel, so gear can sit flush against a wall or the back of a shallow cabinet.
  • One source, two devices. The Toslink splitter splits one optical source to two, with both outputs live at the same time.

Two odd jobs worth knowing about

If your headphone lead is too short, check the size of the jack first. The 6.35 mm headphone extension is the large 6.35 mm (1/4 inch) connector, stereo TRS, in an eight-metre plug-to-socket extension — for amplifiers, mixers, keyboards and studio headphones, not for earbuds.

And to get a camcorder onto a television, the 4-pole 3.5 mm to 3 RCA camcorder lead carries composite video and stereo audio from the camera on a 4-pole 3.5 mm right-angle plug to three RCA plugs. Camcorder AV sockets are not standardised — there is more than one pin order in use — so check your camera's manual or the plug on your original lead before ordering.

Quick reference

Where to start

The leads live in Audio Cables and the adaptors in Plug Adapters / Converters. If you would rather answer a couple of questions than read a list, the Cable Finder narrows it down in a few taps. Still not sure which plug you are holding? Tell us what you have and we will identify it.