Classic B-Format uses scaling factors W=1, X=sqrt(2), Y=sqrt(2), and Z=sqrt(2),
which is +3dB louder than FuMa. The base factors are designed assuming classic
scaling, so encoding a 0dBFS FuMa signal without accounting for this would
result in the UHJ signal peaking at about -3dBFS. Similarly, decoding UHJ to
FuMa B-Format would be +3dB louder than intended.
So encoding needs to implicitly boost the signal by +3dB, and decoding needs to
attenuate by -3dB.
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