for me, i use to have same problem like you guys last time. on my old car with cheapo component set and on my new car with stock speakers. music will start to crack after volume reaches 24-30. after changing to a nice set of component speakers, problem half solved. but i found out that whenever i use those preset EQ's like vocal, superbass, custom, flat and etc, it'll start to sound very sharp and leads to cracking. these "artificial" amplification will only spoil the sound. unless you're those who are happy to blast your music along a quiet neighbourhood or thru a row of mamak with those super sharp treble and muddy bass sound. my friend came into my car and being itchy fingers adjusted the head units EQ to maximum in bass and treble. true it gives a boomy and sharp sound when you play a CD but to me its just noise.
now that i set my HU's EQ to flat, it sounds a lot more natural and doesn't crack at all even though my volume at 55.
