full-frequency neutral clarity combined with mellowness, airy spaciousness with instrumental placement independent of listener position relative to speakers, an utterly undistorted and unfatiguing ease to the presentation that allows for unself-conscious listening for hours and hours to where one loses track of time.
Describe your preference in a single sentence
Although I don't have enough exposure or experience like some of the more seasoned audiophiles on this site, nonetheless I have gone through 10-12 integrated amps (tubes and SS) in the last 5 years. There are a few sound quality attributes that I have come to realize that I prioritize over everything else. But if I have to describe it in a single sentence, it will be "thou shall never ever sound lean!"
And it's precisely for this reason I keep going back to tubes.
Let's share your top priorities in a single sentence :)