Qinpu A-6500 Desktop Vacuum Tube Hi-Fi Amplifier The Qinpu A-6500 is a compact, affordable tube amplifier designed to drive quality headphones or boo Updated and improved from the previous model A-6000MKII, the A-6500 features an advanced circuit des It has ample power to drive quality headphones, even ones that are power hungry It also features a subwoofer output for low-end frequency enhancement.