ifi Zen Stream Measurements and intro to streamers

Zen Stream: https://ifi-audio.com/products/zen-stream/

ChitChat:

Streamers are becoming increasingly popular nowadays, and I’m very glad that’s the case.
Personally, I think that a beefy gaming PC is literally THE worst possible thing you can have in an audio chain, and getting away from that, even just to something basic like a raspberry pi, can bring a surprising improvement to setups regardless of price or performance level.
A PC is horrifically noisy from an electrical standpoint, and also typically has poor to awful jitter and scheduling on SPDIF and USB.

A dedicated device, such as this zen stream, is a fantastic way to get a nice bump in sound quality which applies to any chain.
For those who just want to plug and play and have everything done though, without configuring a pi themselves, ifi has released the Zen Stream.
A full review of this unit is coming, and it will be VERY positive cause this is a great bit of kit.
But for now, here’s some measurements to compare to other streamers and DDCs like the pi2aes, DI20HE and Singxer SU-6.


Test Setup:

– Audio Precision APx555 B-Series Analyzer
– AudioQuest Carbon SPDIF Cable (1.5m)
– ifi iPower 15v PSU
– Netgear network switch, CAT7 Ethernet cable
– 44.1khz and 48khz white noise played through device during measurement

Measurements:

Jitter:

To measure jitter, the device is connected to the digital input of the APx555, and the analyzer is set to analyze jitter, not audio content.
These measurements do not show audio/analog info, but instead show the spectrum of jitter, ie: time-domain inconsistencies.
This is the primary factor that a good streamer or DDC will seek to improve.

I’ll be posting some measurements of other DDCs/Streamers shortly, so if you’re not sure what to compare this to yet, you won’t have to wait too long!

Absolutely fantastic performance here, Audible-band jitter is exceptional and HF jitter is still very low too.
Not quite as good as 48khz, but still very good. The ~2.5khz, 5khz and 10khz spikes are a little odd, but still very low and again, great performance.

Electrical Noise:

The second issue that a good DDC or Streamer will seek to address is electrical noise. You don’t want noise from your source causing your DAC to perform poorly. Noise can have a direct, audible effect, such as hearing GPU-whine through your headphones/speakers, or it can have indirectly-audible effects. For example, causing clocks in your dac, or other circuitry, to perform sub-optimally.
Some dacs are more immune to this, and some will even have full galvanic isolation to in theory prevent any noise getting through entirely. But many smaller dacs are much more susceptible to it.

The Zen-Stream comes with a high quality iPower PSU, and ifi says it has Active-noise-cancellation tech on the outputs.
As the measurements show, clearly whatever ifi is doing is working:

This is seriously fantastic noise levels, absolutely nothing here that anyone could possibly consider anything but fantastic. Well done ifi!
Even if for some reason your dac was so horribly designed that it just put all of this noise directly through to the output, it’d be at -107dB relative to 4v (in the 20hz-20khz band).

Also worth noting that the zen stream disables the SPDIF output when nothing is playing, so noise measurement must be taken whilst something is being put through the streamer.

4 thoughts on “ifi Zen Stream Measurements and intro to streamers”

  1. Very good practice. How comes that noise in the plot is in nano and micro range, depending on frequency, and then the RMS is in millivolt range? There seems to be something wrong. Thanks

    Reply
  2. The RMS is integrated over the audio bandwidth so to get from the noise versus freq plot to a single RMS number you need to multiply it with the square root of the bandwidth, which is about 142 for a 20kHz band.

    Jan

    Reply

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