Cayin c5 portable hifi headphone amplifier the cayin c5 portable headphone amplifier is a portable powerhouse perfect for listening on the go its sleek yet robust aluminium casing is durable and provides excellent protection against electromagnetic interference inside the casing youll find dedicated high performance audio components including an opa134 amp and lme49600 buffer a japanese precision alps volume pot fujitsus premium hi fi relay german wima capacitors a texas instruments hi fi head