would a multi channel upgrade do much?

Thanks in advance for opinions.

Currently i have 2 15" rockford subs with an old 1000a2 amp and then i have kenwood excellons in the rear 6x9 and rockford components up front (not sure which ones were there when i bought the car)  hooked up in my 2nd gen eclipse GS (1998) the speakers are hooked up to a 240.4 right now and i am kind of toying with the idea of getting another 1000a2 but decided today that they are already physically abusive (but they give a hell of a back massage) so i thought i might upgrade mids and highs so that if i do get another 1000a2 i don't have more bass than my mids and highs can keep up with (i am more for sound quality than big hits, but when i can get both together than i'm really happy) soo my question is if i got something like a https://cgi.ebay.com/OLD-SCHOOL-ROCKFORD-FOSGATE-PUNCH-400a4-NICE_W0QQitemZ120089957940QQihZ002QQcategoryZ39737QQssPageNameZWDVWQQrdZ1QQcmdZViewItem 400a4 to replace the 240.4 would i hear much of a difference overall would it be worth the hassle of switching amps and spending the money?

Thanks and sorry for the rambling.

Check the power ratings on your speakers, might have to keep the gains pretty low.  Regardless its always best to have more power than you need at hand, the amp runs cooler, and you never know when your going to want to upgrade speakers.

Is there a crossover at play here?  If not, highly recommended - any lil houndred dollar one will do the trick enough.