I just noticed that Richard of BitPerfect has posted part four of his DirectStream review:
http://bitperfectsound.blogspot.com/2014/11/directstream-iv.html
Here are some old threads discussing the earlier three parts:
http://www.psaudio.com/forum/directstream-all-about-it/new-review-posted/
http://www.psaudio.com/forum/directstream-all-about-it/bitstream-ds-review/