With my IEMs I find it loud enough. As mentioned if you use the stock music player run adapt sound it increases the volume.
Otherwise you can install a kernel like Faux kernel and he has implemented sound control you can increase the gain and boost volume even louder if you wish.
Or you can install Viper4Android and boost volume on that too.
Sent from my GT-I9505 using Tapatalk
Phone: Samsung Galaxy S4 I9505
Rom: AOSP GE 4.4.2 by Danvdh - Fast! | Der Kernel: KT Kernel
Tablet: Nexus 7 2013 32GB
Rom: OmniRom 4.4.2 | Der Kernel: Stock Omni
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