Well then V4A may be the solution for your hardware.
I'm assuming you have a 5.1 or higher sound system running through the pass through on your TV. V4A installs a whole new sound driver. And is very configurable after that. I think V4A will think it is a phone speaker which doesn't have assss much configuration as if it detected itself being connected via headset(3.5mm)/USB dock/Bluetooth. But if ya play with it.... You should find an improvement.
@SkOrPn
+1 V4A !!
It rocks and will give you plenty of options to customize your sound.
The included V4A sound driver usually offers a vast improvement in over all sound quality so hopefully solves your problem.
If you want a more basic app I would recommend to try Dolby Atmos (also compliments V4A very well) from xda;
*excellent intelligent & customisable EQ
*option to boost dialogue/voices
*option to boost/level overall volume
*virtual surround sound option
NB I cannot confirm if this app works on NP
@ElfinJNoty
If you want to make use of the V4A settings available in the other tabs (eg Analog X, DDC or VHS+ etc from Headset/Bluetooth) for normal/speaker output;
*Use the 'Lock Effect Mode' menu option to apply only one group of settings to all enabled outputs.
Goodluck and hope this helps !!