How to restart tube amp and pre in boxes for 2yrs

Swampwalker, great idea! A variac is the way I do it with equipment that's been off for a few years or more. I will usually pull the output tubes, and monitor the voltages from the tube sockets. Contact the manufacturer just to make sure it's safe to pull the output tubes. With the output tubes pulled I only run the variac up to 110Vac. Internal voltages will be higher because you have the output tubes pulled and you don't want to over voltage the caps. Or let a tech do it for you. I'm on the west coast.

Two years is not a long time to be sitting idle. The electrolytic caps should be okay (assuming they were okay going into storage).

You should not have a problem with speakers not attached if you don't put a signal into the amp.

Elizabeth's approach would be a not to difficult to implement safety measure. Be sure to have a reasonably long time between turning on the amp again. Some tubes hate being turned on again immediately after being turned off. If I do that with my power amps, I sometimes get a tiny flash from the rectifier.

Important that you bring the amps to room temperature of 72 degrees for at least a day. Never start them otherwise. Second the load comment.

Larryi..You're actually at an advantage having a tube rectifier. The tubes running off that rectifier (high voltage) have a nice soft start. No tube will conduct until the rectifier starts conducting and turns on, minimizing the inrush current. Tube units with solid state rectification are a different story. Voltage appears at the tubes before they have a chance to conduct. The inrush current is not minimized and there is no soft start. That makes it much harder for old capacitors to form up, and puts a strain on the power transformer. The flash you see on the rectifier is because there is no soft start for the rectifier. It provides a soft start for everything in the circuit it feeds.