Pi 2 Design - 502DAC - Pro Audio Shield

I use the 502DAC with DietPI as a Roon endpoint. I did have to select it in the DietPi Audio config (hifiberry digi+ pro), and then it showed in Roon as an endpoint. I am using the balanced AES output to feed my Schiit Yaggdrasil. It works perfectly! and sounds great! There is not a case for it as far as I know. Someone on their forum asked this same question and got no response.

Otherwise though, the 502DAC has been rock solid in balanced digital out mode. I can’t speak of the DAC part, since I use the digital out.


No metal case is planned, but we did do an acrylic one. It should be ready in just a week or two. Anyone who bought a 502DAC will get one free with only shipping cost required. There will also be one for the 502AES as well as our upcoming 502HTA (Hybrid Tube Amp replacing the 503HTA) and our 502DAC2 (AK4490EQ) and 502DAC3 (PCM1798) each with an LME49720/ME49600 Headphone Amp. The 502DAC2/3 will be compatible with the Digi+ Pro and will have the same digital outputs as the 502DAC.

I will be posting datasheets, manuals and 3D renders over the next few weeks on our web site: www.pi2design.com.


Oh my, this is super impressive. Nice linear regulator used too (LT3042).

I’m not sure how these HATs have gone under the radar here. I have a feeling you’ll be getting busy.

With the 502DAC, can the HAT and Pi boards be powered independently?

Is there any resistor that needs to be removed or pin broken for using 2 independent 5Vdc power supplies?

502AES? Is that available now? I didn’t need the DAC on my 502 since I only use the AES. If you are releasing a AES only version I may dive in, and move my to another location and use the DAC.

The hat can be powered from an external supply or from the Pi. With an external supply you can also power the PI at the same time, or use a separate power supply for the Pi. There is a jumper on the hat that controls this.


502AES is coning September. 502DAC is in stock now. It has Toslink, isolated AES Coax/RCA (we supply the BNC to RCA adapter) and isolated AES balanced via 1/4" TRS jack (we supply the 1/4" to XLR male adapter).

The main benefits of the 502AES is IS2 over HDMI and isolated external clock in option.


Fantastic, thanks Michael.

The 502AES will include Toslink also?

And I know you said details are still coming with the 502DAC2 and 502DAC3 but are both planned to include DSD128 support (the D to A conversion)?

No, the 502AES does not include Toslink. We had to make room for the full size XLR and the HDMI.

As for DSD, because the source of the stream is the Pi itself, DSD is not supported AFAIK. Maybe there is DoP translator on some Pi player out there? My guess is no, but I have not looked myself.


Not a problem.

And for the digital outputs, there will be zero design differences between the current 502DAC and upcoming 502DAC2 and 502DAC3, right?

Only the analogue stages will be different between these 3 HAT’s?

I would be interested in an AES for HDMI to my AVR. I may go ahead and pull the trigger on HiFiBerry to get my newbie feet wet, but I would really prefer HDMI to AVR capabilities.

Hi David, this is I2S (the language that most DACs speak) via a HDMI connector. Not the typical HDMI found in AVR’s.

So while it uses typical HDMI connectors and typical HDMI cables, it’s not the same as typical HDMI for video and picture.

I think… Michael can correct me

so 502DAC2 (Ak4490EQ) is more advanced than the 502DAC. And the 502DAC3 is even superior? What is the ETA of these?

And how do you think they compare to Allo Boss DAC in SQ?

Hi Tomasz they aren’t released yet. Michael said above that more technical info will be released over the next weeks . The 502DAC uses nice components. We’ll know over the next months of comparisons.

1 Like

Hi @Michael_Kelly

Can you kindly explain how the 502DAC’s TOSlink output is powered?

Assuming I power the 502DAC and Pi3 board’s separately, does the 502DAC’s board 5Vdc input pass through the LT3042 regulator at all, to the Toslink connector?

Or does the 5Vdc input go direct to a voltage divider at the Toslink connector?

And for powering the Toslink output, is it exactly the same for the upcoming 502DAC2 and 502DAC3? Or are there differences?

Many thanks in advance

The TOSLINK is powered directly from the 5V. This is the same for all our hats that have optical out.


Thanks Michael.

Hi @Michael_Kelly

It’s great that the HiFiBerry code has been working without issues so there should be no rush to change but have you got any plans to develop your own code/images for your boards?

And when separate external 5Vdc power is used, does the LT3042 still power both NDK clocks and the WM8804?


502DAC and 502DAC Pro use the same digital section, but in the 502DAC the PCM5122 is the master, while in the 502DAC Pro the WM8804 is the master. 502DAC Pro uses the TI PCM1792 DAC.


Correct, the external 5V is summed with the Pi 5V using a back power protection circuit. This 5V is then sent to the LT3042 LDO.


Sorry, I lost track of this forum when the messages stopped coming to me. I messed up my account!

Anyway, the 502DAC has the TI PCM5122 and the 502DAC Pro (was 502DAC3) uses the TI PCM1792. The 502DAC2 had some issues in the prototype phase so we pulled it. We will probably do a 502DAC Pro version with an AKM DAC in the future, but likely it will be the AK4497EQ.


P.S. We just went live with an Indiegogo campaign for the 502DAC and 502DAC Pro. We plan to do an updated showing Roon running within a week or so. The campaign is at:


Hope to see you there!