Comparing both DACs as they stand, I far prefer the Ref 7.1, as the Calyx sound flat and dull in comparison just using USB power from my MacBook Pro. Using the Audiophilleo 1 + Pure Power for both DACs and the Vaunix Hub as power for the Calyx put them pretty close to each other -- that is, I'd need to compare them in a serious speaker rig I reckon to differentiate them.
correct me if i'm wrong but i'm trying to make sense of your initial review vs what you're saying now. you mentioned that
"Improving on the very good USB input required me using my Audiophilleo 1 + Pure Power with the coax input and then I was well into the law of diminishing returns for the benefits accrued to the sound."
from this I got the impression that the USB was very close to what you got from the usb --> spdif converter added to the chain, yet your last post seems to imply a much greater improvement from the latter chain compared to just USB. Since you could hardly distinguish between the ref 7.1 and this latter chain, as opposed to you "far preferring" the 7.1 over the calyx when used just with USB.
could you clarify?