Coaxial vs Optical Digital Output on a CD Player: Which Should You Use?

If your CD player has both a coaxial and an optical output, you have probably wondered whether one sounds better. The honest answer is that both carry the same digital data, and the difference comes from how the connection behaves in your room, not from some hidden quality in the plug. Still, the two formats are not interchangeable in every setup, and choosing the wrong one can introduce noise, dropouts, or a cable run that will not reach.

What Each Connection Actually Carries

Both outputs send S/PDIF, a consumer digital audio format that carries two channels of PCM audio. Coaxial uses a 75-ohm electrical cable with RCA connectors. Optical uses a fiber cable with Toslink connectors and transmits light instead of voltage. The data is identical, including the sample rate and bit depth, so a disc played through either output reaches your DAC with the same numbers.

Where they differ is the physical path. Electrical cable is vulnerable to ground loops and radio interference. Fiber is immune to both, but it adds two electro-optical conversions and is more fragile at the connector.

The Differences That Actually Matter

Ground isolation

If your CD player and amplifier sit on different circuits, or you hear a faint hum that disappears when you unplug the player, optical is the easy fix. Fiber breaks the electrical connection completely. This is the single strongest reason to choose optical in a mixed setup.

Cable length and routing

Coaxial is practical up to about 10 meters with a decent 75-ohm cable. Optical can run longer in theory, but cheap plastic fiber loses signal over distance and dislikes tight bends. If the cable has to snake behind furniture, coaxial is usually more forgiving.

Jitter and clock recovery

Electrical coax tends to deliver a cleaner clock edge to the DAC, which is why many enthusiasts prefer it. Whether that difference is audible depends on the DAC’s own clocking. A well-designed modern DAC will re-clock both inputs and erase most of the advantage.

Cost and durability

A competent coaxial cable costs less than a competent optical cable, and RCA connectors survive being plugged and unplugged far better than Toslink ports, which are easy to crack or fill with dust.

When Coaxial Is the Better Choice

• Short runs under two meters between player and DAC.
• Equipment sharing one power circuit with no hum issues.
• You swap cables often or move the system regularly.
• You want to spend less on the cable and more on the music.

When Optical Wins

• Audible hum or buzz that survives other troubleshooting.
• Player and amplifier on different outlets or different rooms.
• A TV, PC, or switch-mode supply sits nearby and injects noise.
• You need complete electrical isolation for a measurement rig.

Common Myths Worth Dropping

You will read that optical sounds thin and coaxial sounds warm. Both claims describe a broken or mismatched setup rather than the format. If one input sounds brighter, check the DAC’s input settings, the cable seating, and whether the player is outputting the same sample rate on both. Our explainer on what really comes out of a CD player’s digital output covers why 44.1 kHz matters and why some players alter the stream.

Another myth is that a more expensive cable unlocks detail. With S/PDIF, a cable either passes the data reliably or it does not. Above a basic quality threshold, you are buying build and looks, not sound.

What About Using Both at Once?

Most players output on both connectors simultaneously. That is useful if you want to feed a DAC and a recorder at the same time, but it also means a faulty cable on the unused output can sometimes load the circuit. If you hear clicks or dropouts, unplug the cable you are not using before chasing a repair.

Connecting to an External DAC

The choice of cable matters less than the DAC itself. A budget player feeding a good external DAC usually beats the same player’s analog outputs, because the player’s internal conversion is the weaker link. If you are weighing that upgrade, our comparison of internal versus external DACs in CD players explains what changes and what does not.

A Simple Decision Rule

Start with coaxial if the run is short and the system is hum-free. Switch to optical the moment you hear ground noise you cannot otherwise fix. Keep both cables if you can; they cost little and one of them will save an evening someday.

Plug in one cable, play a familiar disc, then swap and listen again. If you cannot hear a difference, you have your answer: use the one with the better connector on your gear.