I have Samsung Galaxy A12 and it's a weird case. For me the default system EQ (everything is at 0db) sounds worse than if I change anything. Even a 20k -0.5db decrease changes everything. My theory is some Samsung phones basic EQ is actually boosts some frequencies which could cause worse sound. Also some phones have audio settings and you can choose what type of headphones/IEMs you using and it changes the EQ even though the system EQ is at default