Quote Originally Posted by Bill K Davis
I know you shouldn't turn on an amp without speakers attatched. Can headphones be used as a substitute?
Contrary to the information you have, solid state amplifiers CAN be turned on without any speakers attached. As a matter of fact they'll much prefer this condition to having speakers attached! They just don't like to get short circuited at the speaker posts. Any higher impedance, especially infinite impedance (no speakers) is OK.

On the other hand, that information is true for tube amplifiers (or some very special solid state amplifiers with output transformers, such as some McIntosh designs). They don't like operating with no load, just as solid state amplifiers don't like short circuits.