Final result coming soon...
This project is still ongoing. A few trials and tribulations along the way - it wouldn't be a fun hobby unless there were challenges, eh?
I found an interesting fault that I believe I have now diagnosed and have a fix for: the Logitech Transporter designers, in their wisdom used the non-I2S compatible mode for the AKM DAC, hence the data bits are offset by one bit position. All is well (seemingly) with the signal digitally attenuated but hit the top 2 bits and the game is up! So now I need logic to delay the data by 1 bit and it _should_ be good. I'll prototype on breadboard and then if it works, I'll get a new PCB made.
Other than that, all the other modules are built and tested and awaiting this last wrinkle to be ironed out and then I can fully assemble.
Considering that the DAC is running on an attenuated 14 bit signal and on mostly shared bench power supplies it sounds surprisingly good. There is something just a lot more exciting and realistic about the sound compared to the AKM. The AKM sounds fine, provided you don't do direct comparisons but when you do you realize just how much excitement has been lost. I've heard the term "veils" and it sort of fits. A "boring veil", if you will...
Who knows, when it's done and I take it to a meetup, it might sound like sh*te.
