9) troubleshooting

8) smoke test

After circuit and component verification, you are ready for the smoke test. When you are comfortable that all is right with the world, and you have connected the load (speaker) and a source (guitar or mike), energize the amp by first plugging the line cord in, then flipping the power switch to "on". Check to see that the tubes are heating. Important: Always keep one hand in a pocket or behind your back and use a non-conductive pick to poke with. Wear safety glasses to protect against the effects of an unwanted arc or flash.
Be ready to power the amp "off" if an unwanted response is heard over the speaker. Have a nice glass of red wine and pat yourself on the back if the amp works on first attempt.

7) you've completed the wiring; DON'T PLUG IT IN!

When you have completed the wiring, don't plug the amp in. You are not ready for the smoke test yet. There are still some things to do.
a) ensure a speaker (of the proper impedance) is available to "load" the amp. Energizing an unloaded amp could result in damage to components like the output transformer and power amp tubes.
b) verify the circuitry against both the schematic and layout drawings. I found it beneficial to highlight each component and lead on both drawings as I verified them. Take your time here to ensure accuracy.
c) verify the circuitry against both the schematic and layout drawings. It is not a mistake that this step appears twice.