Is it possible to remote on a tube amp

I cannot see that it would be any different from using the power switch on the amp (see last sentence) though the power conditioner may change the sound (for better or for worse). Do you already use the conditioner on the amp? What amp is it and does it have any special features for powering up that will be BI-passed by your proposed method? If you are not sure then you might check with the manufacturer, if possible.

Make sure that conditioner does not limit the current to the tube amp or the tube amps may not sound their best!

Some recommend pluggung yube amplifiers straight into the circuit (20a plus) to avoid current limiting.
Also see the thread(s) on power cords and power conditioners).