Can you comment on the design of the digital audio outputs.
I'm interested in the re clocking & isolation of the USB (dac out) and jitter on the coax s/pdif output.
The Primo had very poor jitter on the s/pdif output so the Rivo sounds like a good solution.
Also on the Primo it was recommended to not use the HDMI out as this would degrade sound.
I'm assuming this is no longer the case with the Rivo ?
Regarding the SPDIF/AES-EBU output, the signal source is the SBC itself (a slightly customized version of VIM3L) which has an excellent SPDIF signal quality to start with.
The signal output from the VIM3L is buffered with a series of Schmitt-trigger inverters, then sent to the 1:1 transformers with high-bandwidth, for galvanic isolation. The signal output stage has it's own dedicated low-noise supply and its own GND plane.
Regarding the USB-DAC port, the 5V output is heavily filtered, with a series of LC blocks (we have ~4600uF in total on the 5V power rail). Each LC block has electrolytic capacitors and low-value ceramic capacitors, for filtering the high-frequency noise.
For the USB signals, we use a USB hub from Microchip (with its own low-noise power supply and GND plane). This IC has proprietary technology to buffer and reconstruct the signals from the host (VIM3L), for recovering signal integrity. The clock input for the USB hub is from a high-precision active clock (with its own low-noise power supply and GND plane). The USB port itself has its own dedicated GND plane.
Audio quality is not affected if HDMI video is used.
