Like some have suggested, I highly suspect that the warm sound the OP is looking for is only available in lower powered tube amps. This will require an efficient speaker.
In addition to my 89db neutral speaker running on a 300wpc neutral ss amp, I have a 100db speaker dedicated to flea watt tube amps starting with the 300b. Bummer it’s not efficient enough for 45 2wpc tube SET amps some say sounds like the best SET tube - I’ll need a much larger speaker (which won’t fit my rooms) to increase efficiency.