Why did my amp just crash and burn ?

chaseton:

In an ideal situation with no music playing there’s no voltage on the outputs of an amp. When you short an amp in this situation you should generate no current.

If your fuse blew it _might_ be an indicator that there’s some DC offset. Meaning that instead of an amp returning to 0V it returns to some value above or below 0 that is significant. Get a multimeter, set it to DC and measure. Value should be under 100mV.

On the other hand, an amp could short from just it’s normal noise.

One other thing to ask, were you playing any music when you moved the cable?

If not, a short would only blow a fuse if you have DC on the amp outputs.  This might be worth checking before reconnecting your speakers.

Hey, you may have a short.  Disconnect the cables from both ends and measure the resistance, should be infinite. Check for even the thinnest of stray copper threads.