So my 2 input (XLR) 8 output (phono/RCA) box had been giving me some worries over the past couple of months, and in fact I gave up on it for a few weeks, But I plugged it all back in last night and... it just works.
Stupidity was the main cause for issue. My output phono sockets on the back actually are ordered as "4 5 6 7 0 1 2 3" to match up with the Sigma Studio output channels. As the ribbon connectors on the buffer PCB and DAC PCB are aligned in the same orientation to the edges of the PCB, when they are put together they are "opposite" and the ribbon cable has to twist 180 degrees to fit. Pretty dumb not to notice it but there we are, humanities flaws being shown in their finest hour.
Simple waveform generator (ancient noisy thing) on the Right channel XLR input, mapped to channel 1 output. And it works (and it works with any other channel combo as well). Nothing special but it's a start, adding crossovers in is just done in the DSP now. Although it won't boot from the EEPROM at the moment, assume I actually put an EEPROM chip in the socket.... maybe I should go check that....
Oh and my maximum output from the buffer board with the dac at 0dB output is 5Vpp, so I need to change a few resistors on the buffer board or some amps will get fried.
An electronics engineer and a long term electronics hobbyist. I like tinkering with stuff and making things.