The default volume in your iPhone is not the maximum that you have. There is an internal app that will help to maximize the volume of your iPhone.
First, keep in view that you have iClarified added as an installer source. You can find directions on how to do that here.
Now, after you have iClarified installed, you have to open the Installer through your Springboard. Then press on Install tab that is located in the bottom of the screen.
You would be shown a list of categories in which you have to select the category “iClarified”.
It will show various packages like Jailbreak, Syncfix, Unlock, Volume Boost.
Select Volume Boost 1.1.4 category and press the install button. It will show a warning message with a large red Install button. Press that and start the installation process.
There will be a confirmation message that “This process will patch your iPhone to increase to its maximum volume. Make sure you are on Firmware 1.1.4”. You just have to click on OK if you are on the right firmware version.
When it’s done, you would be asked to restart the iPhone and the volume is patched. When you restart and play some music, you would see a rise in the volume than before.