Do I need a specific type of 4 gauge wire for my monoblock amp?

120 amp fuse  that  is higher then the current going through any 
wire in you home. Most houses have a 200 amp service for the whole house. Is this amp for a Stadium ?  I have never seen in 
Audio ever a 150 amp fuse 
 

To handle a 150 amp load youwill need a awg-1 gauge 
in a copper wire ,justlook up the awg wire index for 
150 amps and wire size requirement . Something does not sound right ,this is not for a home ,  even on big power amps 
they use only a 20 amp circuit .i owneda Audio store In the UK
and into Audio over 30 years . Something is not right ,
thereos no home amplifier higher then a 15  maybe 20 amp fuse .
you need to tell us what model brand  and age 
call JBL . If this isaindustrial Amplifier for a outdoor concert 
that is a whole different ball game.

This is for a class D monoblock subwoofer amplifier. Crutchfield said I should use one that's at least 120 amp.

The fuse goes between the battery and the amp itself.

Class d amps have a higher output than most other class a or a/b amps.

Go to a professional installer and save yourself the angina!

Crutchfield sells a wiring kit for $70 that has 4 gauge wire and a fuse.

Best

JD