I think the issue is more that descriptive terms are completely objective.
I personally like the X-Sabre's presentation no matter how it's described because I feel it doesn't add or subtract anything significant to / from the sound. That means I can then tweak the sound with tubes etc. if I want to. A previous DAC I used was a bit warm which made it hard to come back to the middle if I wanted to. It's easy to add warmth, but hard to take it away.
Just a comment: if we are talking about acoustic music, in which there is a live reference to gauge the accuracy of the recording, sometimes warmth is more accurate. A good violin timbre is very warm to my ears. Or a Steinway piano. To me, tube equipment is generally more accurate to live music rather than "colored" or having a euphonic distortion. But hey, that's my ears.