"I went into music settings and checkmarked the option to set all songs to the same volume. Now when I increase the volume, the warning message doesn't come up at all, and I can increase volume to the maximum if I want. Finally, I've been trying to fix this problem for ages, and I know others are experiencing this as well! Try this out and give me a shout if it works for you."
Try tweaking that setting in the stock music app.
If that doesn't work for you, you'll have to install the Xposed Framework and enable a module which can disable the setting.
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