Version 1.1.1 came back from the fab, and electrically it works perfectly. Mechanically, there are still some issues.

The biggest one is that the TRS jack just doesn't stick out far enough. Attempting to plug into it doesn't go in far enough before it hits the front panel, so it makes poor contact.

I've decided to bite the bullet and go with dual RCA jacks instead. Surely those will stick out far enough. While I'm at it, I decided to move the TOSLINK jack just a bit further back. Mating hasn't been an issue thus far, but I want to make it even less of a potential one. I might wind up deciding to go with OSHpark's half-thickness boards for the front and back panels as well. We'll see.

The two RCA jacks and the "error" LED barely fit on the front panel of the chassis I sourced, but I am fairly confident that fit they will.

The sounds is just as beautiful as it was before. I'm going to have to find a way to generate some optical test signals and try to measure the S:N of the prototype to see if all of my noise reduction precautions have been sufficient. The plan is to attempt to generate sine tones and look at the output with the FFT mode of my scope to look for spurs and measure the S:N.