I can confirm the validity of Asa Post's impressions on the 808v6. I have listened via MD600 streaming and CD replay.

Importantly for me, with a v3 machine, it was vital that the v6 was a sufficiently strong sound quality up-grade in its own right, independent of MQA ability. Following a trial of a loan machine, this was absolutely the case. I have since up-graded my v3 to v6 as a result.

808v6, DSP7200SE, MD600
Vertex AQ & LeadingEdge products