I recently bought a DAC+ Pro XLR, and am enjoying it very much. However some suggestions to help new customers which maybe the hifiberry team could address:
1. There is advice on connecting the output to unbalanced RCA in the blog https://www.hifiberry.com/blog/the-dac-pro-xlr-what-you-need-to-know/ It says to use an XLR female to RCA adapter cable. However, off-the-shelf adapters and cables all connect pin 3 to ground - with the DAC+ Pro XLR this causes very high distortion at full output. Instead, 'custom' cables should be made with pin 3 left unconnected.
2. I found it difficult to find build instructions for the XLR steel case on the hifiberry website. There is no link under "Documentation - Hardware" or the "Knowledge Base - Cases" sections (where the links for other cases are).... in the end, I had to find it through google.