Level up

Level up your headphone to increase its properties

Level up cost varies and ties with the rarity of the headphones

LC = Level-up cost

R = Current Rarity, Dope =1, Re =2, etc

CL = Current Level

LC(HUT) = 8+ current level * 4 + 10* (R -1)
LC(HBK@level4) = 30 + 20 * (R -1)
LC(HBK@level14) = 80 + 40 * (R -1)
Cooldown time (hours) = (CL + R -1) * 3