Boards of Canada, Jaga Jazzist, Amon Tobin, John Zorn, Seefeel, Tim Hecker, Plaid, Aphex Twin, The Cinematic Orchestra, Clark, Cocteau Twins…

Warmth in the context of HiFi is a character of the sound rather than the sound itself.

At the opposite end of this spectrum is cold or clinical, which shouldn’t be inferred as “bad” or “worse” neccessarily, there’s a time and a place for it - like in the studio where the original source material is being edited, mixed, and mastered.

With this same source material now running through say a nice tube preamp and/or amplifier the character of the sound is softened/rounded via very subtle distortion, subtle enough that all of the detail is still there when it meets your ears.

Warmth is for enjoyment, while cold/clinical is academic.

It was at this point I knew I’d made a terrible mistake. By opening my fat yob of a mouth on the internet, I’d provided an angry redditor their opprortunity to sizzle