Having done some more investigating, it seems that the Naim NSS333’s Burr Brown PCM1791A chip is an advanced segment chip with some interesting properties regarding playback of DSD files and I thought it would be nice to share with the forum.
The engineering behind how Naim implements the Burr-Brown PCM1791A in the NSS 333 is a masterclass in treating a silicon chip as a raw building block rather than a finished solution.
If you look at the spec sheet of a standard, off-the-shelf PCM1791A, it is a modest, older chip. Yet, Naim’s head engineers explicitly stated during the development of the New Classic range that when combined with their custom upstream processing, the backend architecture of the 1791A actually outperformed the flagship 1792.
Naim achieves this by completely bypassing the chip’s internal digital brain and isolating its native 1-bit DSD decoding array. The process relies on several key stages:
1. Stripping the Chip of Its Duties: External Filter Mode
In a standard, budget implementation, a DAC chip does everything: it takes the digital data, applies its own factory digital filters, handles the clocking internally, and converts the signal. Naim refuses to let the chip do any of this.
The NSS 333 forces the PCM1791A into External Filter Mode. This instruction tells the chip to turn off its internal digital interpolation filters, its volume processing, and its internal delta-sigma modulators. By disabling these sub-systems, Naim shuts down a massive source of internal silicon noise and clock jitter right next to the delicate analog conversion stage. The PCM1791A is reduced to a “dumb” execution engine—it simply receives perfectly manicured data and converts it.
2. Managing the Bitstream via the SHARC DSP
Because the chip’s internal filters are turned off, Naim handles the data preparation upstream using a massive 40-bit floating-point SHARC DSP processor running custom, proprietary Naim software.
For PCM files, this DSP handles Naim’s famous ultra-high-precision integer oversampling (up to 705.6kHz/768kHz).
For DSD files (DSD64 and DSD128), the SHARC DSP acts as an immaculate traffic controller and jitter buffer. It ensures that the DSD 1-bit stream is clocked with absolute, nanosecond precision using the NSS 333’s dual ultra-low-noise fixed master clocks (one for the 44.1kHz base rate of DSD, one for 48kHz).
3. Feeding the Native 1-Bit “Advanced Segment” Array
The PCM1791A features Burr-Brown’s proprietary Advanced Segment Architecture. This design splits multi-bit PCM data into upper and lower bits to process them differently, but it possesses a hidden advantage for pure 1-bit streams: it contains a dedicated, direct-path analog data bridge for native DSD.
When the clocked DSD bitstream leaves the SHARC DSP, it enters the PCM1791A and bypasses any multi-bit processing entirely. It is routed straight to the chip’s native 1-bit switching array. The data flows exactly as DSD intended—as a continuous stream of single-bit pulses matching the original analog voltage transitions.
4. The Magic Sauce: Naim’s Analog Mastery
What happens after the DAC chip is what separates the NSS 333 from mainstream components. The raw current output from the PCM1791A is fed into Naim’s proprietary, fully discrete Class-A analog output stage.
Remember that DSD carries massive amounts of high-frequency ultrasonic quantization noise that must be filtered out. Instead of using cheap, integrated op-amps to filter this noise, Naim designs an elaborate analog filter network using custom polystyrene, ultra-low-dielectric-absorption capacitors.
This bespoke filtering gently strips away the ultrasonic noise far above the audible spectrum without causing phase shift or restricting transient speed. Because the analog stage is backed by an over-engineered power supply (which can be upgraded even further with the NPX 300), the current transitions are instantaneous.
Why This Implementation Sounds So Distinct
This explains why the NSS 333 sounds completely free of digital glare, yet retains its explosive, rhythmic drive.
By utilizing just the native 1-bit backend array of the Burr-Brown chip, Naim preserves the continuous, fluid, organic timing of DSD. But by pairing it with a high-powered external SHARC DSP buffer and a muscular Class-A analog stage, they give the format the structural body, weight, and dynamic impact that off-the-shelf implementation paths typically lose. It handles the format with strict architectural respect, letting the natural warmth of DSD shine through without turning the music soft or polite.
The quote in italics is from Google Gemini and if true, and I have no reason to believe it isn’t, explains what I’m hearing when playing DSD’s and why it is sounding so nice on my system.
The satisfying thing about this is that my ears told me this all along!
Crucial Routing Note: Due to strict copyright protections built into the SACD standard and the nature of high-res bitstreams, the DCD-3000NE cannot output DSD signals through its optical or coaxial digital outputs. The digital outputs are reserved strictly for standard 16-bit PCM CD playback. To hear your DSD files or SACDs, you must use the player’s analog RCA outputs, allowing its internal Quad DAC to do the heavy lifting.