Digital sources: DAC, streamer, network
Jitter, isolation and data transport integrity
In digital audio the bits almost always arrive intact: what varies is clock cleanliness and the amount of high-frequency noise riding along to the converter. Optimising a digital source therefore means reducing noise and controlling where the clock lives, not hunting for a magic cable.
Where the clock lives
Asynchronous modes (USB, network) leave the DAC in charge of its own clock, generally the most robust topology. Over S/PDIF or AES the DAC locks to the transport's clock, whose quality then matters a lot.
Modern DACs often resample internally through a buffer, greatly reducing input jitter sensitivity. On those units, swapping digital cables rarely changes anything.
An external clock only helps when the device is designed to use it without an extra recovery loop.
Isolating computer and network noise
Noise from a computer or router arrives mainly through ground: Ethernet, USB, power. Galvanic isolation (Ethernet isolator, a fibre segment, USB isolator) attacks the root cause.
Wired Ethernet beats Wi-Fi for throughput stability, but Wi-Fi removes a ground path: if you hear noise correlated with network activity, test both.
A linear supply replacing a streamer's stock switching brick is often the most audible change in this category.
Digital filters and volume control
Reconstruction filter options (fast, slow, apodising, NOS) change impulse response and are a legitimate listening choice: try them on familiar recordings rather than following theory.
A 32-bit digital volume on a modern DAC is transparent down to -20 or -30 dB. Below that, or at 16/24 bits, you lose resolution: use an analogue preamp instead.
Server-side upsampling guarantees nothing: it moves the work rather than removing it. Compare at matched levels before concluding.
CD/SACD transports and files
A CD transport only has to read data and provide a clean clock: the mechanism matters for read reliability, the power supply for noise. An older player remains relevant as a transport into a current DAC.
Rip your CDs in secure mode and keep lossless files: local playback avoids network and streaming variability.
Verify nothing in the software chain alters the signal: system EQ, resampling to another rate, loudness normalisation.
Common mistakes
- Swapping digital cables before addressing power and ground noise.
- Digital volume set very low into a high-gain amplifier.
- Streamer and router bricks sitting against analogue links.
- Comparing two settings at different levels.
Checklist
- Clock topology identified (DAC master or slave).
- Computer ground path isolated if noise is audible.
- Streamer/DAC power supply addressed.
- Digital volume kept above -20 dB, or analogue preamp used.
- Bit-perfect software chain verified.