It's not exactly that straightforward. In general any modern audio equipment will run up to 20kHz since that's generally accepted as the range of human hearing. From what I can tell, the lowpass filters built in to equipment (eg antialiasing on ADC/DAC) attenuates starting at 19 or 20 kHz. But these are realized as low order physical filters, meaning they roll off slowly, so you'd have to start attenuating at something much lower to truly remove the 18-20 range. That would introduce distortion where the rolloff starts, which you probably don't want.