What am I doing wrong?

[yabaVR]

I think I have now solved my problem, which I should have picked up earlier.

I was using a Tellurium Q Blue Diamond speaker cable. Although this is a good detailed cable I am not sure it is a good match with the Devialet. It gives a sharpness to the upper frequencies that, to my ears, emphasises what I feel is the (relative) weakest aspect of the 120. I have tried a Chord Signature Reference cable and enjoyed the 120 much more.

However, I think I need to resign ignominiously from the forum, because I still prefer the sound of the Superuniti. Less detail, reduced soundstage, but a full rich flow to the music. It's only a matter of emphasis, since they both have much in common and have at their core very good clear amps. And it is clearly purely a personal preference.

I can't bring myself to sell the Devialet. It is now the basis of a very good second system (the cost of which I have not admitted to my wife).

Don't give up on the D120 yet.
The Tellurium is NOT harsh sounding or a bad match for the D120 but lets harshness from up your audio chain 'more thru' vs. the chord being not as transparent.
I've to emphasize it again. Harshness (or annoying highs) comes from Jitter and/or bad power quality that leads a Devialet to produce more and more Jitter in the audio signal. If you listen to a Dxxx connected to a pure/stable powerline and the music source has no Jitter you won't hear any harshness in your music no matter the cables. Though there will allways be a cables being better than the one one owns. That's out of questions 

gui