JL Audio HD600/4 4-Channel AmplifierSmall amps, big power JL Audio's HD Series amplifiers offer high performance from an ultra compact chassis. These Class D amplifiers use less power, take up less space, and generate less heat than traditional amp designs you can even stack them up to create a sweet looking installation. JL Audio technology goes to work for you HD Series amplifiers reproduce your music with exceptional accuracy, so you'll hear high fidelity sound even under the most