Perhaps a distinction should be made between "tube in the signal path amplifer " & "tube output stage amplifier"?
The only classic tube output stage I am aware of is in the Milbert which uses output transformers between the output tubes and the load. (The Zelos shown has some sort of transformer set in there and looks to be on the output stage. I also thought I saw one that TRU had an EL84 w/ output transformer version a couple years back but can't find it now.) If there are others, please post what they are.
Everything else has a tube in the front-end circuitry (& only marginally as pointed out in some of them) and not as part of the output stage of the amplifier at all. That said, I wouldn't call them tube amplifiers just that they have a tube in them.
The only classic tube output stage I am aware of is in the Milbert which uses output transformers between the output tubes and the load. (The Zelos shown has some sort of transformer set in there and looks to be on the output stage. I also thought I saw one that TRU had an EL84 w/ output transformer version a couple years back but can't find it now.) If there are others, please post what they are.
Everything else has a tube in the front-end circuitry (& only marginally as pointed out in some of them) and not as part of the output stage of the amplifier at all. That said, I wouldn't call them tube amplifiers just that they have a tube in them.