Anything I should do before plugging these in? They all appear to be in fine condition. I don't want to lose tubes accidentally. Most of my experience is solid state. And what's worth refurbing?

I don't think you'll damage tubes, they're pretty rugged. If they're not spent already, I don't think you'll hurt them with a power-on surge or anything. The filament voltage is usually set by a transformer secondary.

The components I find bad most often are capacitors. Many times the tubes are in great shape. A tube doesn't go bad in storage like a capacitor does. So check the capacitors, especially electrolytics.

• Variac