Fiio am5 high powered headphone amplifier module for fiio x7 the new am5 amplifier for the fiio x7 is a replaceableupgraded amplifier unit that you can use to change the sound quality of your fiio x7 and is designed to power the more power hungry headphones out there perfect for those with headphones with high impedance the am5 uses the muses02 by muses the audiophile semiconductor division of the new janpan radio co ltd for voltage amplification like the am2 with the tpa6120a2 a curr