Got new subs. 4000watt amp. All wired correctly. Worked fine for a week.

Today they stopped working.
The amp insignia is backlit and still lights up.
And the amp hums slightly as if it is working.
(It has always done this)
But neither the power nor the protect light light up at all.
The car runs fine.
Could this be a result of needing a high output alternator?
I am allso using smaller gauge power and ground wires than recommended.
I'm not sure if that could also be a factor.?

Any solutions to get me bumping again?