Headphone manufacturer listed frequency range is generally useless since they don't show you any FR curve. They put big number there so it is easier to sell to average consumer who believe bigger number must be better - but human only listen up to around 20kHz, and that is when you are teen. Most adult listens up 16~17kHz. Any half decent headphone amp will have frequency range much greater than human listening range. My advice? Don't worry about matching frequency range. The real important question is, do you really need an amp at all?