You probably could run the 804s with a push pull tube amp. I wouldn’t. I prefer solid-state over push pull tube amps. Don’t confuse the loose bass of a tube amp losing control of the speaker with tube magic. It isn’t. The real magic in tube amps is single ended triode paired with the right speaker. See my prior post. My 802D3s have got pretty good sensitivity. But, Impedance curve and phase angle are horrific! Impedance drops below 2 ohms at certain frequencies. Despite their relatively good sensitivity, they are a very difficult load for any amplifier. You don’t want to run those with a single ended 3 watt amplifier.
Search enough and you will find that many like me that have been up to the edge with systems approaching $100,000 chasing the dragon and then discover what we’ve been looking for all along was hiding under our nose. We were afraid of the flea watt moniker. Again, the rest of the equipment is imperative. Especially the speakers and EQ. No exceptions.
We’re all different. Maybe you wouldn’t like it. But I and many others wish we had gone that route first. More enjoyment at a fraction of the cost. What’s not to like?