[AT&T Samsung Galaxy Note 4] DroidBlaze:
One root mod/app I miss quite a bit is Viper4Android. It makes a HUGE difference to audio quality. Even more so on a smartphone with a subpar DAC such as our note 4 (the exynos variants are excluded since they have a Wolfson DAC). Due to the lack of root on the ATT note 4, I've been carrying a secondary device with Viper4Android to enjoy my music with headphones. But not anymore. I've found the next best thing and NO ROOT required. Truthfully, it's not as good as V4A; but it's definitely an improvement over everything else I've tried so far on the note 4. It is called Noozxoide EIZO-rewire PRO.

KitKat Setup:

Install from the play store here

Go to Settings>Sound>Music effects and select Noozxoide

You should be good to go

Enjoy

Lollipop Setup:

Install from the play store here

Go to Settings>Application manager

Swipe to the "ALL" tab

Find "SoundAlive" and disable it

(not sure if this is needed but just in case) Now find "Package Adapt Sound" and also disable it

Noozxoide should now work

Enjoy

Tips:

Get rid of persistent icon/notification -

When you see the app's icon in the status bar, pull down the notification shade and select the noozxoide notification. Untick the box for "Show notifications" and voila no more constant icon in status bar.

Sound quality/app settings:

I personally only bother with the "LINE-OUT" option since that's the one that corresponds to the aux jack.

By just having Noozxoide as the default EQ and all options unchecked in the app I noticed an improvement in sound quality.

- Check the box for "Deliver balanced natural soundstage and premium bass" and select one of the digital presets. Different presets give a different sound signature. Try each and select what sounds best to you.

- *Apparently "VE-Engine (Volume Enhancement)" does not work for our Qualcomm DAC so don't use this*

- For more warmth and bass check the box for "Increase the monitor size with added psycho-acoustic" and again select the effect strength. WARNING! The bass can get very strong!

- For wider soundstage and surround sound check the box for "Create VSUR on practical monitors and widen soundstage" and select one of the room sizes.

My personal settings:

I generally only check the first box and select the "Audiophile" preset. That's it. However, when using closed-back over ear headphones and listening to EDM, I pump up a bit of the bass for some eargasmic, soul crushing bass.

A couple of points I'd like to make:

1. Like I previously stated, I only care about the "LINE-OUT" option. I didn't bother checking out the "BUILT-IN" (speaker) or "WIRELESS" (Bluetooth) options.

2. It is recommended to use good headphones/earphones/speakers to get the most out of this app. Otherwise you might not hear a difference compared to the stock SoundAlive.

3. DOES work with ART and Lollipop

4. MOST IMPORTANTLY, audio quality can very subjective so what sounds good to me may not sound good to you. Try different options and hopefully something will sound good to YOU. If you end up agreeing with me that this is the next best thing to V4A, then you are welcome. Enjoy!

One last thing:

You might ask yourself, "why bother with this if I'm happy with the sound quality of -insert favorite music player-?" The answer is simple. Music players like PowerAmp sound great for playing back music located locally on the phone. However, what if you want great sound quality of all audio play back including streaming music apps like Google Play Music, Pandora, Spotify, etc? That's where this gem of an app comes in :highfive:.

I am not the dev of this app. All credit goes to dogsbark.