Answering my own question in part, I found this review in Hi Fi World: http://www.hi-fiworld.co.uk/index.php/av-receivers/39-av-reviews/199-onkyo-pr-sc886.html?start=1

A key point: Distortion was very low at 0.0002% and noise also low at -90dB at full gain, Direct or Pure Direct selected, lowering to 85dB through the input A/D.

What can be the problem. It also lauds the MM input and the DACS.