I've been listening to the latest round of delta-sigma DACs—at substantial price points of more than $6000—and for reasons I don't completely understand, they sound alike, and quite different than the $1100 Monarchy N24 that I've had for the last ten years. The technologies are pretty different: the N24 uses the TI/Burr-Brown PCM1704 ladder/R-2R converter, passive current-to-voltage conversion, with zero-feedback vacuum-tube amplification. ...
The delta-sigma DACs I've been auditioning use a completely different architecture; delta-sigma chips from Crystal Semiconductor, Analog Devices, and the ESS Sabre 9018, along with all-solid-state electronics. Some of these use opamps, some discrete FETs and bipolar transistors, but they all have a common sound—what I'm beginning to think of as the "delta-sigma" sound.
What's going on here? I hear it in my iPod Touch driving Sennheiser HD580 headphones, I hear in my Marantz AV8003 pre-pro that I use for movies, and I hear it in the latest group of DACs. Yes, they all sound modern and up-to-date; smooth, pleasant, free of the grit-and-grain that plagued early digital, and play 88.2, 96, and 192 kHz digital with the greatest of ease. But there's something missing. I don't have any fancy audiophile words for it, but it's an absence of life, of sparkle, of that intangible sense of being right in the room with the performer.
If a singer in singing right at the ragged edge of their vocal range—and doing it intentionally to create a sense of tension—it is (much) less noticeable with DACs using delta-sigma chipsets. The impression of physical texture—a hand lightly brushing across the head of a drum, the sensation of wood and steel and weight from a grand piano, the odd and fascinating tonal meanderings of an oboe—is diminished or absent. In the highest-quality DAC with the ESS Sabre 9018 converter, it's subtle, and takes a quick comparison with the PCM-1704 DAC to hear the difference. In the most other delta-sigma DACs, the loss is not subtle at all, and the performers sound bored, like they're just phoning-in the performance. The nuances and over-the-top aspects are absent, replaced by a sort of monotone quality.
After a while, I kind of get used to this sound—the audiophile virtues of clarity, dimension and smoothness are certainly all there with the best of the high-end DACs—but then switch back to the Monarchy using the Burr-Brown PCM-1704 DAC and go "AH!". All the vividness and tone color suddenly returns, and the performers, instruments and hall-space sound real again.