after experimenting with IOS and Android devices in my G, I thought I would share my findings ...
the EQ the Bose amp applies sucks the life out of the music. the factory Bose speakers (when used with a powered sub) can sound pretty good when the EQ is "fixed". the treble in particular is harsh and lacks clarity/crispness.

- the best sound i've found is with an old rooted Android smartphone running the Viper4Android app. when adjusted right, it just sounds fantastic.
PROS: great audio
CONS: no album art (on Bluetooth), battery doesn't last if the car sits for a few days (newer phone with a larger battery might help, the one i used is ancient )

- the latest setup i'm using is an iPhone 5C i bought used for cheap to just leave in the car. had to buy that, because most music player apps with adjustable EQ won't run on anything earlier than IOS 7 (like my iPod Touch 4 ). i'm using the free HS Player app https://itunes.apple.com/us/app/hs-p...857650606?mt=8 with 10-band EQ. i dial down the treble a lot on the headunit, and the bass a bit, and tweak to my liking with the HS Player EQ. there may be some other apps that work, too, but this was free and i didn't feel like blowing money on ones that may or may not work. i tried the BBE Sonicmax and Audio Xciter apps, but they screw up the song info and album art.
PROS: good audio, album art and song info works, battery life better
CONS: not as much tweakability as V4A on Android

let me know if any other IOS apps work better ... hope this helps.

HS Player: