I need help i have Alpine SPS-609 (6"x9" 3-way 260w car speakers) and Alpine SPS-406 (4"x6" 2-way 140w car speakers) the 6x9's sound amazing and are extremely loud but when i turn my head unit up the 4x6's start to crackle and squeal on certain songs is there a problem? or do i need to upgrade the speakers in the front and if i do what kind of speakers should i go with?
Odds are the 4x6 Speakers are maxing out and are not able to handle what your 6x9's can. Either that or they are damaged.
I'd first make sure that all of your connections are solid and that nothing is loose. If everything looks good, attempt to upgrade your speakers.
If you do not have the funds to upgrade better quality speakers, see if your deck has an Equalizer or Fader to focus more on the 6x9 Speakers than the 4x6 Speakers.