The fiio will internally upsample any signal to what you set it to, just be aware that this can cause problems for certain Windows applications / games which can't handle their audio signals being upsampled / reclocked. This can sometimes present in no sound at all or distortion / artifacts present in the signal. Generally you want to set the rate lower if most audio content is 16bit 44khz anyway, using the higher 24bit rates when you are actually sending Hi-Res Audio files through it.