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

For a cheap way to be safe, plug them in and turn them on for only a moment. Fast on off for LESS than a second. wait twenty minutes or so. Flip them on again, but leave on for three seconds, then off. wait an hour. Turn them on for a thirty seconds, then off for a few hours. They should be good to go.
This is a 'sort-of' variac approach. the caps need to be babied, and the momentary turn on, then longer do the same job, only for free.

i read a caution that tube amps need to be hooked up to a speaker load at all times when turned on. can anybody verify this?

Most tube amps are supposed to be operated only w a load (speaker or resistor across outputs) but I have no idea if this applies to the momentary on-off approach Elizabeth advocates. Best approach is to use a variac and bring the voltage up very, very slowly to allow the capacitors to "re-form" (whatever that means). 2 years is not that long, you might want to ask Chris @ Parts Express who does a lot of modification work on SF gear and I think used to be involved with that company (maybe co-owner??).