Just make sure that your tube amp has plenty of clearance, so the heat has a place to dissipate.
As for your burn-in question. Why not just burn in the speakers in while you are listening to them and get to know your new speakers. If you must perform the burn in ahead of critical listening, run your amp several hours at time for X number of days.
I accept the need to burn in, I just never bought into having to burn in equipment for a large number of hours.
Rich