Speaker cable might look like just a bit of wire that connects your speaker to the audio system, but it is critical in determining the quality of audio output. Wires that can sustain high voltages and provide a continuous current signal are the best because they minimise distortion or loss of sound signal. Whatever material the speaker wire is made of, it's ultimately the thickness and length of the cable that decides how well the speakers perform.
Consider the gauge. Gauge refers to the thickness of a wire, and it can range from 18 to 10. Wires with a lower gauge contain a thicker copper conductor, so they are better at conducting audio signals.
Take the length of the wire connecting the amplifier and the speaker into account to decide the gauge to use. Generally, if the speakers are close to the AV receiver and the cable length is less than 50 feet, use 16 gauge wire. For lengths between 50 and 100 feet, use 14 gauge wire; use 12 gauge wire for lengths ranging between 100 and 150 feet. Beyond 150 feet, stick to 10 gauge wire.
Find out the material of construction. Cables made of oxygen-free copper, or OFC, or high conductive silver have slightly lower resistance than similar gauge standard copper wires. Check the impedance of your speaker as mentioned in the manual. Compare this with the resistance of the speaker cable before selecting one. Choose a cable that has very less resistance compared with the speaker impedance. Thus, the material of the speaker cable is immaterial in most cases. Beware of hype about OFC and silver wires, which are significantly more expensive than standard copper wire.
Consider the sound effect desired. Multi-stranded wire is made up of many wires, with small diameters, which are separately insulated. The lower diameter makes the highs smoother. Choose a speaker cable made of multi-stranded wire rather than solid speaker wire for a better audio experience. Moreover, when many small diameter wires are present, the total diameter is greater, giving rise to a large-gauge wire, which causes a deep bass effect.
Gauge 16 speaker cable is very easy to handle because it is thin--this allows it to pass easily under carpets and along door frames. It is also less expensive than other gauge cables. In general, longer speaker cables tend to have less ability to transmit sound of higher frequency. It is therefore better to select shorter speaker cables and use them by keeping the speaker closer to the amplifier. Avoid low quality speaker cables -- they are often insufficiently insulated and this can lead to corrosion of the copper wire within the cable.