Hi Fred,
I had used TL51X during 2006 to 2007 period. The digital output problem is made by CEC since they set a relay on the digital output. I can't said it is a bug of this product. I would like to said it is a sales technique because the CEC company really want you to buy the whole set of CEC product.
If you want to use their digital output, you need to short the AES/EBU pins to each other to make it done.
That's my own experience. And you need to do this process after you switch off the TL51X every time.
Hope you can enjoy the music from TL51X soon.
If you don't mind, I would like to know the performance of the Mytek DAC since I am planning to buy one soon.
Regards,
Tony