I think you are missing how much the spectrum of the drift matters. Just knowing the range over which the clock varies (say 5%) isn't enough. If the drift is sl

I think you are missing how much the spectrum of the drift matters. Just knowing the range over which the clock varies (say 5%) isn't enough. If the drift is slow - which thermally induced drift usually is, because it's driven by daily heating/cooling cycles - then it's possible to correct for it in the recording. Analysis techniques which are based on frequency-domain variations would tend to reject this type of slow drift automatically, but the details depend on the technique used. If, on the other hand, the noise on the clock is fast jitter rather than slow drift, things become much more difficult. On typical consumer recording devices, the noise floor due to jitter is way below the noise floor due to the limited SNR of the microphones and amplifiers used. The jitter noise is non-linear, which makes things harder, but doesn't tend to be a limiting factor. It's been most of a decade since I worked on this stuff (in the context of radar and sonar), so that knowledge may be out of date. Still, I'd be surprised if clock (LO) jitter is the limiting factor in this type of analysis.