Let me resurrect this thread a bit. I finally bought a silver BDP-105 and I also currently have the NAD M51. Overall, I like the M51 better due to its more refined and neutral presentation as well as having wider & deeper soundstage. I also notice a more solid imaging together with noticeably better bass response on the Nad. On a side note, I also found the Oppo to be near identical sonically to my W4S DAC-2 after several back-and-forth comparisons. In the end, I preferred the W4S to the Oppo due to slighty better extension on both ends of the spectrum. IMO, of course.