You shouldn't. In theory, the purpose of an amp-cab (speaker) cable is to deliver a signal in the quickest and most energy efficient way possible from your amplifier to the cabinet, and for this, an unshielded, thick, & low-resistance speaker cable is necessary. As opposed to a high-impedance, shielded instrument cable, which protects and controls the sound incoming from your instrument by preventing RF & EM interference, overloads, and other risks of noise.