If there is an impedance stated near the amplifier' speaker output jack, do not use a speaker combination lower than this stated value. Use a thick wired zip cord for speaker hookup. This is specially true for bass, where damping factor, tone and watts could be easily lost. However, if your are experiencing radio or T. V. interference, a shielded guitar cable might help out with this problem, as the culprit interfering radio frequency energy could enter your amp through a speaker cable, as well as through the input cables. Additionally, shielded coaxial cables used in the speaker path might cause some amplifiers to break into uncontrollable and dangerous oscillations.
Caution is advised here.
If the amp doesn't sound right or if it behaves oddly after installation of a shielded coaxial speaker cable, go back to using the zip cord type. If you hear the amp cutting in and out, reduce the amp volume then wiggle the speaker cord. An intermittently open or shorted speaker connection or cord might blow up your amplifier. This one is very important. Keep all cable ends clean.