bob olhsson wrote:32 bits is very common in the I2S interface. Also, the DAC chip itself may be using 32 bit processing for the filter, volume control, ASRC, etc.
AES/EBU truncates to 24 bits so the 32 bit converters are probably only 32 bit using their USB input.
The new ESS chip is squeezing another couple dB of THD+N out, but I fear the push to ever-lower supply voltages and dissipation requirements (most new technology is driven by mobile phones, not audio DAC's, after all) will make these converters the ones to beat for the foreseeable future.
Yes, that's exactly right, ESS claim of their flagship ES9018:
"The SABRE 32 Reference audio DAC’s 32-bit Hyperstream architecture can handle full 32-bit PCM data via I2S input..."
"The SABRE 32 consumes less than 100mW"
And they also list "64-bit accumulator and 32-bit processing" in the datasheet
The THD is listed as -120dB in Mono, Stereo or 8 channel mode (which is 19.93 bits) and in Stereo mode they claim a dynamic range of 133dB (22 bits!!)
As we know, dither makes the resolution infinite, and as Paul Frindle noted in the Oxford manual, properly dithered signals can be recovered 120dB below the noise floor.
We can see in the ESS ES9018 DAC, which is the current state of the art converter technology, and designated as a "32-bit" DAC, that it is producing THD levels 24dB above even the theoretical
quantization error of 24 bit PCM.
Mark my words, this is a truly remarkable feat.
But is it 32 bits? No.
It will certainly never reproduce truncation distortion in a 24 bit file, and probably not in a 20 bit file.
Viva la Resolution..!!