iFi Zen Can Signature for Sennheiser HD 6XX HeadphonesLevel up The original ZEN CAN, our all analogue headphone amplifier, boasted the ability to drive tough headphone loads, a balanced circuit design, vanishingly low levels of distortion and versatile sonic tailoring. The ZEN CAN Signature 6XX takes this to another level. It further improves the sound quality with enhanced circuit design, whilst maintaining the versatile features of the regular version and adding something special a custom EQ setting