In the past three years I have seen 2 subs brown up by what you are proposing and one user who tried, only to not use the system as it was so unfriendly. All decided they could do this despite my advice. All had studdied Ohms law..... The latter was simply solved by a cheap receiver and the guy is happy. One of the other guys is still badgering me to fix his 'pride and joy'. I have refused due to his stupidity despite good advice.
You asked will it help? and anyadvice appreciated. You didn't ask for the risks to be explained to you. Both of you questions were answered.
If you have am amp why do you want to risk catastrophy? seems daft to me but hey what do I know about these thing