Why not just vent the heat out of the room? A ceiling vent isn't expensive to install and some dryer duct hose will send it out of the house with the help of an inexpensive low speed fan. Then air conditioning won't have any trouble keeping up; you may not even need it.
But here's the thing. Most tube amps get docked about heat due to the filaments of the tubes. Literally the only tube where this is a thing is the 6C33; with any octal-based power tubes the heat contributed by the filament is inconsequential. So that means most of the heat is coming from the class of operation, and will be about the same amount as a solid state amp running the same class of operation and making the same power. I know this because our amps make about as much heat as any for their power, but if in Standby (no B+ on the power tubes) you can have the amps on all day and walk up to them and grab a power tube and hang on. They just aren't that hot.
The only way I can think of to get away from that is a class D amplifier. So if that's out of the question, then do vents in the ceiling. It will cost a few hundred dollars but you can have the fan operated by a wall switch and no impact from the heat of the amps in your room as long as the vents are above the amps (heat rises, after all...).
But here's the thing. Most tube amps get docked about heat due to the filaments of the tubes. Literally the only tube where this is a thing is the 6C33; with any octal-based power tubes the heat contributed by the filament is inconsequential. So that means most of the heat is coming from the class of operation, and will be about the same amount as a solid state amp running the same class of operation and making the same power. I know this because our amps make about as much heat as any for their power, but if in Standby (no B+ on the power tubes) you can have the amps on all day and walk up to them and grab a power tube and hang on. They just aren't that hot.
The only way I can think of to get away from that is a class D amplifier. So if that's out of the question, then do vents in the ceiling. It will cost a few hundred dollars but you can have the fan operated by a wall switch and no impact from the heat of the amps in your room as long as the vents are above the amps (heat rises, after all...).