I bought the dac from a regular here on audiocircle and have used it very little. I bought it to connect my tv to my system, and it turned out that I just didn't use it like that.
I did confirm that it worked with the toslink input. I've also listened to music through the rca input, but I have not used the usb input.
There are no mods that I'm aware of. I believe it is the "first generation" valab nos dac.
I forgot to take a picture before packing it up, but it looks just like this one:
Please let me know if you have any more questions.