Note that I haven't purchased any of the add-ons (see below). I just use AEM to capture audio which then goes straight into my desktop DAW. I don't mix on it.
 
The following in-app purchases are available to expand your studio:

• USB audio interface support (you can also purchase USB Audio Recorder PRO). Please see our compatibility list here https://www.extreamsd.com/USBAudioRecorderPRO and for more information here: http://www.audio-evolutio...php?id=usbaudiosupport
• FX pack 1 (distortion, overdrive, speaker sim, wah wah, phaser)
• FX pack 2 (10-, 15-, 30-band graphic EQ)
• ToneBoosters pack 1 (Barricade, DeEsser, Gate, Reverb)
• ToneBoosters EQ with frequency analyzer
• ToneBoosters Compressor
• ToneBoosters Ferox
• Vocal Tune with two-voice harmonizer
• Loop/sample packs
• Soundfont packs
 

FYI, turns out Stage Assistant needs to be connected to a USB MIDI interface/controller; you can't simply load songs onto an SD card or into a tablet and play them from there.  So that's out. :(
 
I'll keep looking at other suggestions in this thread.

jyoung60
I'll keep looking at other suggestions in this thread.

This is a DJ app, but maybe it's all you need.
 
https://play.google.com/store/apps/details?id=jp.pioneer.prosv.android.rbm
 

jyoung60 Failing that, do you know of any good, free, WAV players for Android, that supports playlists? 

use the built in media player ?

pwalpwal
use the built in media player ?

That's one of the first things I tried a couple years ago, but there was something about it that didn't suit my needs.  Possibly the lack of non-autoplay of the next song or something.
 
VLC isn't bad, but there's a very audible 'thump' in the sound when I tap play for each song.  Not good coming through a PA system on stage.