I have all Audio Research Reference gear… nearly 40 tubes. 140 watts per channel. I just went over and held my hand around one of the power tubes… it was slightly hot… touching it, it felt very warm… maybe hot… but you would have to work to get it to burn you. The preamp has 7 tubes is slightly warm. On top of unit.
I have a large room, never noticed it warming the room… but when it 100+ degrees out my air conditioner is on. It does nothing to warm the room.
I seriously doubt my listening amounts to more than a couple dollars a month.
‘’The design does determine the heat. Some designers use the tubes to their max and will generate more heat and shorter tube life. My tube life is over 3,000 hours per set.
To me this is completely a non-issue compared with the incredible sound quality you get with a great tube amp.