From the web sites I have seen you can put a max of 150 amp fuse on 4 gauge wire. If 80 amps pops then try 100 or 125 and see if that pops. By the way what is the fuse in the amp? 4 gauge wire10 feet long should take 120 or 125 amps with no problem.
I am putting together a amp/sub unit that can be used inside through an outlet (custom project). I am running a 300W amp and a 400W RMS Sub. I am currently making the step-down from 120V to 12V and came across the question "how many amps?" How many amps do I need to run the amplifyer? Do amplifyers have maxes for amps they can pull? I am going to buy a power supply once I know how many amps I need. Thanks for any help!
The amount of current a power supply delivers depends on the load. A 80 amp power supply wouldn't hurt anything. Those curent ratings merely describe the MAXIMUM amount of current they can deliver so if you think that amp will draw 25 amps then I'd definitely look into at least a 25 amp power supply.
I'm sure you've found that power supplies that big can get pretty pricey. You might be better off investing your money in a monoblock or bridegable amp designed for home use or better yet a powered subwoofer. You'd probably be much more satisfied with the sound quality of a good powered sub and it sure would be less of a headache to set up.