In case these wire gauge recommendations seem too large to you, you may confirm these values by using our wire calculator.
The wire calculator calculates the wire's resistance and the voltage drop at 20 ° C. Then chose the wire diameter, that should be at least as large as indicated in the DIN table below. Finally you should enter the maximum current that you amplifier "draws".
The voltage drop should be below 0.2 Volt for high-end applications and below 0.5 Volt for standard ones.