Good high-gain amp chip
A high current, high power op amp designed to work with a split supply voltage |V+| + |V-| = 12 Volts or a single supply voltage of 12 Volts would meet the requirement. 

Consider the Texas Instruments OPA549 high voltage high current operational amplifier, which can drive a sustained output current of up to 8 Amperes continuously, and works with supply voltages from 8 Volts to 60 Volts.

Keep in mind that this part (and others like it) is useful primarily at audio frequencies: A low Gain-Bandwidth Product of just 900 KHz would constrain its use for frequencies far beyond the audible range.