In my case, when I slowly migrated through 70s-90s velvety sounding mosfet solid state amplifiers I then moved towards EL34 / KT88 ultralinear and other triode tube amps still holding some of that same type of familiar golden era velvety sound. Speakers are all over the map. I’ll won't digress into a rabbit hole too much.
Later I jumped into newer generation point-to-point wired mono tube amplifiers with modern transformers and KT150 output tubes, a more ’linear sound" or new "HiFi Sound" comments started to surface in different tube amp forum circles.
I probably align with prior posts about how more clarity, transparency, and resulting detail could be characterized by some as being a new/different type of sound compared to the older "golden era" days of equipment and HiFi sound.
Fortunately, keeping preamps / amps / tubes / speakers of both types around.
Thanks for the fun and interesting replies so far - keep them coming folks! 👍