@Alan, Brent thank you, interested by any feedback/comparaison with the Bridge2, sure :).
I went to the point where I change my mind. My initial project was to build a chain without an USB to I2S conversion component, I mean a chain where the computer delivers the I2S output connected to an I2S/HDMI (I2S in LVDS) module linked to the DSD DAC.
However, I do not master sufficiently how to manage the I2S output on a Raspberry or NanoPI. A HifiBerry DAC + Pro is able to deliver an I2S output and is using a quality clock (not the more rated but a good one). So, a HifiBerry DAC + Pro could be a solution and may be the awaited new Allo Kali board but not yet released.
Instead, I purchased an Armature Hecate board http://www.audiophonics.fr/fr/interfaces/armature-hecate-interface-xmos-xcore-208-usb-spdif-asynchrone-version-diy-p-11413.html
This board presents 3 interesting points:
- Use an XMOS 208 processor to manage the USB flow and its multiple formats (DSD included) up to 384Khz and DSD256 native or DoP
- Built around two low jitter Crystek clocks
- Has an galvanic isolation on all of its outpus
- SPDIF (RCA) output and I2S output
- the Hecate board is powered by the USB port (so the NanoPI ou RPI3 in my case)
The only concern is that the I2S output is not in LVDS so the IS2/HDMI module (from AudioGD) is required for our famous and beloved PSaudio DACs.
The galvanic isolation seems to me a very good point, because even if I use a well estimated iFi Audio iPower PSU to power my NanoPI (or RaspberryPI3), I’m thinking that the PSU quality does not need to be at the quality level of a LPS-1 for exemple, because of the isolation offered by the Hecate board. And when I’ll add/plug the I2S/HDMI module on the Hecate’s I2S, I could choose a LPS-1 to power the HDMI module which consume only 30mA, thus far away from the 1A or more required by the PI + the XMOS208/Hecate board. My purpose is to build a very low power SuperCap PSU for 50mA or 100mA max which just sufficient for the I2S/HDMI module. So the PSU should require only few SuperCaps capacity at a low voltage (3,3V in nominal).
Now the sound quality Connected for the moment on my NanoPI with DietPI and Roon, I only tested the SPDIF output. Amazing how good I gained in transparency and precision everywhere. The soundstage is fantastic. All is more real.
What surprised me is to obtain such result on the SPDIF input of the DSD senior while I believed that the best option was either the USB or 2S inputs. For the moment the Hecate board is floating in the Air as I still not installed it in an aluminum case, but very happy by the change. I can play DSD in DoP up to DSD64, I configured Roon to downsample in consequence all higher frequencies because even if the XMOS 208 processor is able to deal higher frequencies we are limited by the SPDIF specification on the DAC.