The conclusion that the Ayre QB-9 is less musical is ... odd.
An Ayre QB-9 was used in an all Ayre, solid state system driving SF Cremonas versus the Metrum being used in an all Shindo system, lush beautiful tube gear driving Devore Gibbon 9s.
The disclaimer is made that this is not an apples to apples comparison. No kidding, it's about as far from apples to apples as you can get. This is like comparing a Rolls Royce on one day to a Ferrari on another and saying the Ferrari is faster but the Rolls is more luxurious, and wondering, "Huh. Could it be the shoes I was wearing?"
I've had both the Ayre and Metrum in my system. The same system, in my room. I found the Metrum more clinical and the Ayre more musical, but neither was as resolving or as musical as the PS Audio PerfectWave DAC.