1 year ago

JustBoom DAC HAT review

Music sounds better with a HAT on

The JustBoom range of Pi products comprises three main types – DAC, Amp, and Digi – featuring different sets of outputs for different uses. Each is available in full-size HAT and Pi Zero-size pHAT form, ready-assembled. All are based on the I2S (inter-IC sound) standard.

The full article can be found in The MagPi 56 and was written by Phil King.

Here we’re taking a look at the DAC HAT, which delivers its sound via an amplified 3.5mm headphone socket, or twin RCA outputs connected to a hi-fi system or powered speakers. While the HAT features a 384kHz/32-bit DAC chip (the TI PCM5122), this is limited by the Pi’s Linux drivers to 192kHz. Nevertheless, the sound quality proved mightily impressive in our tests. Both CD-quality 16-bit tracks and 24-bit HD audio files were played with crystal clarity, even via a modest Sony mini hi-fi system. Classical music in particular benefits from the enhanced clarity and detail.

The DAC HAT comes pre-assembled, so you just need to mount it securely on the Raspberry Pi using the supplied plastic spacers and bolts. As well as slots for Camera Module and touchscreen cables, this well-designed HAT features a full (unpopulated) GPIO breakout. The packaging includes an optional IR receiver, for you to solder on if you want to use a remote control. There’s also the option to fit the HAT in a sleek plastic case (£13 / $17).

It’s then a case of deciding which OS to use. A whole host are supported, including Volumio, OSMC, OpenELEC, Roon, and Max2Play (for which a 30-day free trial is included). Most are easy to set up with the HAT. In Raspbian, it involves commenting out one line in /boot/config.txt and adding three, one of which enables playback from Sonic Pi. A quick reboot and it’s ready to use, although we found we needed to boost the digital volume in alsamixer for headphone playback.

One final trick up the DAC HAT’s sleeve is the ability to stack a standalone Amp board (£60 / $79) on top, featuring block terminals so you can connect it directly to passive speakers. You’ll need an additional power supply to get full power (30W RMS) out of it.

Last word


Delivering audiophile sound at an affordable price, the well-designed DAC HAT is an impressive piece of kit. It offers a huge improvement in quality over the Pi’s standard 3.5mm audio jack, and sounds particularly impressive when playing back lossless formats.