The Pi2AES is a device I love. It’s very affordable at just $199, way less than most streamers especially good ones, and it has some absolutely exceptional performance, even beating out the $1000 Denafrips Hermes DDC.
If you’ve not seen my video on digital sources and would like a bit of info as to why they can be beneficial you can watch it here:
This article will provide some measurements of the Pi2AES as well as instructions on how to do the ‘5v direct’ reversible mod in order to use a 5v psu of your choice, and reduce noise.
– Pi2aes is great
– I2S > SPDIF > BNC > AES > Optical (For pi2aes anyway, this will not be the same for all devices)
– 5v PSU mod reduces noise slightly (if you use a good PSU)
– Audio Precision APx555 B-Series Analyzer
– AudioQuest Carbon SPDIF, BNC and AES Cables (all 1.5m)
– ifi iPower 5v
– Netgear network switch, CAT7 Ethernet cable
– 44.1khz and 48khz real music played through device during measurement
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!
Unfortunately I can’t measure the I2S output as the APx555 does not support differential/LVDS I2S, but as shown in my DDC video, the performance is absolutely stellar, and it did show measurably lower jitter in a J-Test than the already great performance coax output did. If you have I2S, definitely use it.
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 Pi2AES normally comes with a 24v PSU, though can be used with a PSU up to 48v. This then goes through an on-board switcher to step it down to 5v. Personally I’m not a fan of this aspect, both because having an additional switcher when it isn’t needed seems odd, but also because the pi also runs on 5v, and so just having an input for 5v would make getting a nice linear PSU etc much easier.
BUT, there is a fairly easy mod to use any 5v psu of your choice instead of 24v. Let’s check to see if it improves things first:
NOTE: The high level of noise at 50hz and multiples thereof is due to the fact that the outputs on the pi2aes are floating. Grounding the device to the analyzer removes this entirely.
We get pretty good noise levels no matter what, not at the same insanely good level as the zen stream but still very low.
But, we can also see that the 5v psu mod, where I used an ifi iPower, does make an improvement.
It’s also a hell of a lot more convenient to use a 5v PSU than a 24v one, so how do you do this?
5v PSU Mod:
You’ll need the following:
– Male to female jumper cables (Can be found on amazon for pennies)
– DC Barrel adapter (again, cheap as chips on amazon)
– 5v PSU (Rated for at least 2.5A) of your choice, the ifi iPower 5v is a great affordable option.
- Disconnect the pi/pi2aes from everything
- Open the top of the case to access the pins
- Make sure that the 5v Jumper shown below is installed. If you are wanting to power the pi separately, remove this jumper, but with this mod (and with the stock PSU) you can power the pi and pi2aes with one PSU by leaving this jumper installed.
4. Take two jumper wires. Ideally different colours, I like to use one ‘dull’ and one ‘bright’ colour so it’s easy to remember which one is 5v and which is ground. Connect the female end of one wire to the 5v pin and the other to the GND pin shown below
5. Connect the male ends of each wire to the DC barrel adapter. Make sure to put the 5v wire into the ‘+’ terminal and the GND wire into the ‘-‘ terminal. Screw the clamps down tight.
6. it should now look like this:
7. Plug your PSU of choice into the DC adapter and away you go!
You can also blu-tac or glue the barrel adapter to the outside of the case to keep things neat. There is a hole in the case just above where these pins are so it’s easy to feed them through as you put the case back together.