JustBoom DAC HAT for the Raspberry Pi

From the creators of pi-supply.com a new DAC to please our ears

Posted on December 18, 2016 by @lorenzoferrara

ATTENTION: We want to make clear that the following opinions are not backed-up by any scientifically accurate data and that the test have been made using the equipment we own. So, please, keep this in mind while posting comments. Thank you.

JustBoom, the team behind Pi Supply, has introduced a new family of Raspberry Pi related audio devices. From DACs to amps, they cover both the Raspberry Pi (classic) and Raspberry Pi Zero computers, giving users the possibility to choose between eight new boards.

The creators where so kind to send me two devices, the JustBoom DAC HAT and the JustBoom Amp HAT, both for the bigger Raspberry Pi. This review is going to cover the JustBoom DAC HAT.

Don't have time to read? Skip to the conclusions.


The box containing the board is very curated and what's inside is even better: you get two JustBoom stickers, an invite to try Roon, a one month Max2Play license, an invite to check out the JustBoom website, and the board. The board is enclosed in a protective, non transparent, black bag, which builds up the curiosity of wanting to see how the device looks like. Inside the bag you find the red board. It's nice that the JustBoom team decided to make the boards all of the same colour, that triggers the brain to associate the keywords dac, raspberry, and red to JustBoom. The package includes a Vishay TSOP4838 infrared receiver to be used in with JustBoom IR Remote. Be aware that if you want to use the IR receiver you must solder it to the board.

The case

Another important piece of the puzzle is the case. All JustBoom boards have a compatible case that can be purchased separately. A case helps you keep the board and the Raspberry Pi protected from shocks and dust. The JustBoom DAC HAT case does its job but leaves some slots open, as you can see from the images above, because it's also compatible with the JustBoom Amp HAT mounted on top of the DAC. Once the Amp HAT is attached to the DAC, the holes will expose the Amp connectors. I would have preferred a more sealed case, maybe with the Amp HAT holes that could be opened breaking the pieces of plastic. I also had some problems mounting the rubber feets (I punctured two of them) but they did fit nicely at the end.

The board

First thing that got my attention is the built quality. The bord is straight and when attached to the Raspberry Pi is very steady. The DAC HAT uses a Texas Instruments PCM5122 32bit, 384kHz DAC (limited to 192kHz due to Linux driver restrictions). A Texas Instruments TPA6133A2 provides a 138mW amplifier for headphones. The board can be used with the Raspberry Pi A+, B+, 2 B, 3 B and also with the Raspberry Pi Zero (but the dedicated DAC Zero pHAT is recommended). Output are two RCA and a 3.5mm jack connection for headphones. The board is powered from the Raspberry Pi GPIO and it's compatible with the JustBoom Amp HAT. Also, there are no headers for connecting the DAC to the dedicated amplifier board, but there are spring connectors that touch the contacts of the JustBoom Amp when stacked one on top of the other.


The sound coming out of the DAC is very good, and, while listening to some of my favorite music, I can hear details that I know I can't hear with all DACs I've tried (this is one the first thing I search for while trying DACs). The PCM5122 chip does its job perfectly. Naturally, the chip is important but not the only important thing, the circuitry, which changes from DAC to DAC, is also a key element. The circuitry can ruin the performances of a good chip, and this is not the case with this DAC. It's important to underline the fact that I test the DACs mainly via headphones, because that's how I like to listen to music.


The JustBoom team provides a custom Max2Play image that makes configuring the board a piece of cake. You really don't need to do much more than selecting the correct DAC board from the homepage of Max2Play and a clicking the confirm button. The choice of supporting Max2Play is great, the image provides everything you need, from listening audio to watching films. They also officially support Volumio, while the product page lists compatiblity with OSMC, RuneAudio, Moode, PiCorePlayer, PiMusicBox, and OpenELEC.


JustBoom is investing a lot in helping their users get up and running with the boards as easily as possible. On the Get Started with JustBoom! page they provide guides for board assembly, amp assembly and case assembly. They also have a dedicated page for Software Guides, but at this day it's a bit empty. For does interested in getting info on the connectors, there is a JustBoom Boards Pinout page and for those interested in the apms spes, there is a JustBoom Amps Use Cases and Usage Configurations page.


The PCM5122 is always a good choice for clean, natural, and detailed sound. The way the JustBoom Amp stacks on the DAC gives you a very compact final unit. Also, the good looking boxing and the possibility to add a case and a remote control, completes the full picture. Considering that the JustBoom DAC costs between 30€ and 40€ (depending on where you buy it), you get a lot from it, especially adding the optional parts (amp, case, remote). The JustBoom team did a very good job.