Amp upgrade

Hey everyone,

Been looking to upgrade the audio in my car. I've already installed 6.5" coaxial speakers in the front and rear. Tweeters are stock and rear sub is stock. I'm currently looking at getting an amp.

My original plan was to get a sub and a 5 channel amp to connect my 4 speakers and sub to. Also looked into a 4 channel amp and omit getting a sub but not sure if I'll be able to connect tweeters along with my speakers.

I've been reading a lot about the Phantom Audio upgrade. Since I've already changed my stock speakers, would that make any difference with the Phantom Audio amp upgrade? I like the idea of just plug and play and the price would be the same for a 5 channel amp, not counting parts and labor. I'm also looking to upgrade my headunit for a 7" touchscreen with Android auto so just seeing if the Phantom Audio would make more of a difference with aftermarket parts or if it's just meant for the stock speakers/headunit.