This is very interesting and brings me to a related problem: If the SNR depends on the frequency band of interest, at what stage should one apply the respective narrowband filters? Let’s use the example of SSVEP. If I want to investigate the corresponding sources at the two distinct frequency bands, is it better to narrowband filter the activity around 12/15 Hz and use the respective frequency-specific SNR for the inverse operator but risk inducing temporal correlations in the noise-covariance violating its assumption of uncorrelated noise (as suggested in this old discussion). Or would you rather choose a common SNR of 1, reconstruct the sources, and narrowband filter the signals in source space? At least to me, it makes more sense to use the complete information of the broadband for the source reconstruction with a common SNR and then narrowband filter in the source space (which comes with its own problems of dipole orientations etc.). Any thoughts?