[Verizon Samsung Galaxy S 4] kvswim:
Thank you so much for putting this in! Like mrtruckincowboy said, this is now working. I HIGHLY recommend this to anyone who listens to music on a regular basis! It really makes a difference with decent headphones! I'm no audiophile, but I definitely enjoy quality over whatever stock crap gets loaded on here. Viper greatly enhances audio, and can even make your phone speaker ridiculously loud with the right settings.

What I did:

Download the latest Viper4android version http://vipersaudio.com/blog/?page_id=48

Unzip

Copy the 4.x version to /system/app and set permissions to rw-r-r.

Edit /system/build.prop: set lpa.decode to false, add tunnel.decode=false and lpa.use-stagefright=false. Save.

Reboot.

Launch the Viper4android app, grant SU and wait for a prompt to pop up asking to install the driver. Press yes, and select "Super Audio Quality".

After it says successful, close the prompts, press menu and set the UI setting to Expert. This unlocks all settings.

Reboot again.

Go to system settings, sound, and set Music effects to Viper4android.

Launch the app. The rest is up to you. Play around with it to get settings YOU like! Notice there are different settings for headphones, phone speaker, and bluetooth. To check if the driver is working, while audio is playing through headphones (or whatever you have settings changed) go into the Viper app and press menu, Driver Status. If you see two yes, it's working! Setting changes usually happen in realtime.

Extras:

If you want IRS (impulse response profiles, recommended!) go download it from http://vipersaudio.com/blog/?page_id=115, unzip it and copy all IRS files to /sdcard/Viper4android/kernel. Go back to the app and you can select one from the Convolver section.

My personal settings: (I have Klipsch Image S4 earbuds so YMMV) I'm only going to list things I have enabled to save space. If it's not listed, it's left stock/disabled.

PlaybackAGC enabled, slight effect, infinite gain, 0 dB max output (optional, makes it louder but has some aliasing when music itself is low/soft. Basically tries to make all levels of sound equalized. Alternatively use Output Gain)

Convolver enabled, with "JoeMeek SC2 High Ratio" profile. (the SPL profiles are also some of my favorites)

Dynamic Listening enabled, high end headphone V2, +40% bass

CureTech+ enabled, slight binaural level

To make your phone speaker obnoxiously loud:

Equalizer enabled, flat setting

Convolver, "JoeMeek SC2 Impulse Soft" (prevents annoying shrill tones), 80% channel crossover

Speaker optimization enabled

Extra loud enabled, extreme effect, infinite gain, 0 dB

+6dB output gain, 0 dB limiter

This will be noticeably louder than your plebeian iPhone peers. Have fun with it.

Note: the Pandora app is very hit and miss, at least with old versions of Viper. I haven't had time to see whether it constantly works. So far, it is. If it doesn't, it's not a fault of Viper or your phone, the Pandora app is kind of weird in its audio playback.

Sorry if none of this makes sense. It's like 2:15 AM here and I've had four hours of sleep in the past two days. I'm just really excited to see this working.

Will this be baked into future builds? Perfectly fine if it's not as long as the commits are in place. Thanks again for doing this, my phone is now complete until KitKat.