I work for Klipsch so please understand these are my personal preference and not at ALL affiliated or endorsed by Klipsch. I have a set of 70th anniversary Khorn.
My room is rectangular and the Khorns are in the corners of the long wall.
Wood floor and the room is not complete yet...but I have done a ton of listening. I also have a lot of vintage speakers, and high efficiency speakers with low power SET or Push Pull amps are my preference-but I have a pure class A 25 watt amp and an 80 watt hybrid.
I have been listening a lot to a 32 watt push pull (Leben) and an 8 watt 300b SET amp. They sound very different, the 300b is romantic, its not necessarily "accurate" reproduction, it does midrange amazing, but the bass is as you can imagine not as controlled or authoritative. Volume wise I can't at all imagine you "need" more volume, but everyone is different.
I have a 2.5 watt 45 tube and haven't yet hooked that up.
I listen to most everything except for country. Have 5 turntables in the house and also do streaming and computer audio.
If you want something that sounds radically different from the Yamaha, or want to truly hear what tubes can do right, I would look at something like a push pull amp using EL84 tubes, should net 12-14 watts. If you can live with lower overall volume capabilities and aren't after bass so much as you are tone and as you stated warmth, to me that comes more from SET than push pull. There are always tradeoffs, but when I hear, Vinyl and warmth, I immediately go to SET and low power push pull. I don't want to generalize, but based on what you described above, something like KT66, KT88, KT120 leads closer to solid state than warm tube sound...