ViPER4Android is a revolutionary audio equalizer for Android, something that I personally can't live without. That's the reason why porting V4A to the LG V20 was the first thing I did when I got the phone. There are two variants of ViPER4Android: FX and XHiFi. XHiFi is an older version which isn't developed anymore, but has amazing audio reconstruction capabilities. FX, on the other hand, has at least three times as many options and features as XHiFi without the audio reconstruction.
The great thing about V4A FX and XHiFi is that they can work in conjunction, since they install and run separate audio drivers. Even though XHiFi hasn't been updated since 2013, it still runs flawlessly on the latest version of Android. ViPER4Android does require a few things before it'll work without any hitches—namely BusyBox and root, as well as TWRP to flash the ZIP and install the mod—but the set-up process itself is fairly easy.
The first step to installing ViPER4Android is ensuring that the BusyBox commands are installed in the /system/xbin directory on your device. The reason for this is that ViPER4Android XHiFi is an older equalizer which only checks for BusyBox in that location, so having it installed there is a must. The simplest way to check the installation location is via the BusyBox application.
So to verify this, open your BusyBox app and read the message near the top of the screen that says BusyBox is installed to—if it doesn't say /system/xbin here, tap the second drop down menu, then select /system/xbin from the list, and press the "Install" button at the bottom of the screen.
The meat-and-potatoes behind this mod is a flashable ZIP that I created which contains both Viper equalizers and the audio drivers. This means you won't have to install drivers and reboot again after installing the initial mod, like you would with other versions of V4A. So to start, tap the following link to download my custom version of the ViPER4Android mod, which was built upon work done by developer zhuhang.
The next step is to simply reboot into TWRP and flash the ZIP you just downloaded. So from TWRP's main menu, press "Install," then navigate to your device's Download folder. From there, select the ViPER4Android.zip file, then swipe the slider at the bottom of the screen to install it. When that's finished, simply tap "Reboot System."
After you've flashed the ViPER4Android ZIP, all that's left to do is to set up the equalizers as you see fit. The ZIP also includes a couple hundred Impulse Response Samples, which can be found in the Convolver section of the ViPER4Android FX app that you'll now find in your app drawer. It's an advanced preset selection, usually built off of the equalizers on other phones with high-end EQs, such as BeatsAudio and HTC Boom. So it'll take some experimenting to find the perfect equalizer preset for your tastes, but there are plenty of options to choose from.
Be sure to let us know if this ViPER4Android installation works for you, and how much different the audio quality playback sounds to you. This port was done to ensure every single feature of ViPER4Android is made available, and while an older version of ViPER4Android FX was included in this port, it was done so for a very good reason: This version of V4A FX has much higher audio processing compared to the newer versions.
Once you've had a chance to play around with ViPER4Android, don't forget to share your thoughts and experiences with us in the comment section below!