I saw no harm when I left my amps on, but the brown-out is always a fear and may damage your speakers too. If you are using tubes, or class-A transistors the heat and the component wear is also something to consider. As a rule, I leave digital components and preamps on, but switch off the power amps.
Leaving Amps on
I am wondering, in the case of which is best for the speaker, is it best to leave the amps on all the time, or shut them off between use. I know that turning them on and off causes heat expansion in voice coils leading to stretching; The main reason that pro audio setups that are permanent stay powered up all the time. But, is it really best? Can I also cause long term damage to the speaker by leaving it powered up with no signal being sent? I just recently read an article that said too much continuous power can burn the parts in the coil. Can anyone help? Thanks in Advanced! Sam