This tip is about casters and tube amps. After playing for many hours a tube amp gets hot. Very hot. Even with a cooling fan there is a certain degree of heat buildup in the chassis and tubes. If your amp has casters, rolling a hot tube amp over a rough surface can weaken or damage your tubes and internal components from the excessive vibrations. This tip also applies to cooled down tube amps but to a lesser degree. There are a few remedies for this. 1- You can just carry the amp rather than rolling it on those little casters. 2- Use a small folding hand truck with soft rubber wheels. The wheels will absorb some of the vibrations and the angle at which you lean the hand truck back offsets some of the vibrations as well. 3- Transport your amp in a flight case. The larger casters and internal foam absorbs some of the vibrations and gives your amp a smooth ride and ultimate protection. So the bottom line is excessive vibrations from rolling your hot (or cool) tube amp is not a good idea. Eliminating unnecessary vibrations can extend the life of your tubes and help keep your amp out of the shop and on the stage where it belongs!