I've just bought my self a Digitech Whammy, and I remember being told once that you should never run a bass through a guitar amp, because the bass frequencies will break the amp, or something like that.
So my question is, if I use the octave down function on the Whammy (i.e. making the guitar have the same range as a bass guitar) will I not risk damaging my amp?

Putting a Bass through a Guitar Amp will not automatically 'break the amp'.. i believe it can cause harm if it's turned up very loud. As the bass frequencies may be too much for the Speakers. - I've ran a bass through a few guitar amps before at loud-ish volumes, with no problems at all.
If they designed it for guitars and added a downtune for guitar, do you think they might have tested it through a guitar amp?

You should be fine.
Quote by corduroyEW
Cheap amps are "that bad". They suck up your tone like cocaine at Kate Moss' party.

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