Not sure if this is technically feasible (to link the spectrum maximum to the current audio device sample rate), but would be welcome for those of us who use sample rates with higher Nyquist frequencies than 20kHz (44.1, 48, etc.)
(I know I know, you can't really hear above ~20kHz anyways, but that information can still be useful for resampling purposes and/or mixing and mastering, where every frequency counts when it comes to dynamics)