Hello Djtek184,
Thanks for reaching out to us for support. It’s never fun when sound check on your iPhone is not working as expected on your device, and we are going to do everything we can to help you. When you have a free moment, please give the steps below a try:
1 - Quit the Music app and Settings on your iPhone with these steps: How to force an app to close on your iPhone, iPad, or iPod touch.
2 - Restart your iPhone.
3 - Try engaging Sound Check again.
4 - If there is still no change with Sound Check, see if any of the equalizers change the sound quality as mentioned here: Change the way music sounds on iPhone.
If you’re still experiencing the same problem after completing the steps above, and there is no change with the EQ settings, please do not hesitate to let us know.
Cheers!