Zapco Z-3KD-II Mono Class D Sound Q AmplifierThe Zapco Z Series II Amplifiers. In 2012 Zapco introduced the new Z Series of SQ amps. These amps were not conceived so much by our engineers, as by input from audiophiles and car sound fanatics around the world. We experimented with internal components and new circuits to see if we could take our amps to the next level of sound quality by investing in higher SQ parts and circuit designs. The resulting Z Series amps were the product of this unique