2x oversampling works better than 4-16x oversampling in some circumstances

[pdesaulniers]

Reported by @unfa: SSR-2021-09-17_12.55.07.webm

I'm not sure, but it seems like the lowpass filter becomes less steep at higher sample rates, which causes aliasing.

[unfa]

This is strange. Because a higher internal sample rate would also give the lowpass filter much more headroom to do a good job, so this should be a problem!