Audio Systems: My amp blew, awg wires, amp fuse

Question
Hi, im running a 4 AWG 12v power from battery to a power distribution block where i split the 4 AWGe to (2)8 AWG wires that lead to 2 amps. I have a 40 fuse before the distribution block. I also have 4 AWG ground wire from battery to a ground distribution block that split the 4 AWG to (2) 8 AWG as well. My amp is a visonik v417sx, 800 W 4 channel amplifier with variable crossover.
LPF, FLAT, HPF
50Hz - 250Hz Low Pass Filter
50Hz - 250Hz High Pass Filter
High Level Input
 
4 x 100W Rms @ 4§Ù Stereo
4 x 150W Rms @ 2§Ù Stereo
2 x 400W Max @ 4§Ù Bridged  

My speakers were not plugged in at the time. Why did it blow?

Answer
A 40 Amp fuse allows only a 480 watt draw from the battery (40a X 12v = 480W).  It could take out the fuse during the power up cycle if the amplifier did a big gurgle.

But, I suspect one or more of the output transistors has shorted down.

Does it blow each time you power up?  If so, you clearly need to check the output devices.

If it blew only once, try getting it on and connecting only one speaker at a time - gently - and see what happens.

Then, let me know more if you don't find the problem.

Cleggsan