"John Phillips" wrote
in message

I looked up the details of the chipset. It seems that
the SAA7030 does the interpolation and does a large part
of the reconstruction filtering. It has a 96-point FIR
filter at 4x input rate with a 28-bit accumulator (16-bit
data, 12-bit coefficients).

The thing that struck me from the datasheet is that the
28 bit accumulator seems to get truncated without dither
to 14 bits and then sent to the DAC (a TDA1540).

The filter acts like an integrator and averages 4 samples to create a sample
with higher accuracy. My understanding of how this works suggests that the
final result would have about the same dynamic range as an ideal 15 bit DAC.
IOW, the LSB is toggling noisily.

Am I correct in thinking this undithered truncation is
likely to generate significant quantization error?

No, because there is no truncation in the final result.