The Saramonic Smartmix is an almost all-in-one audio mixer for (ANY phone) and has built in audio or allows you to plug in an external mic - geekazine.com 
# Main Features - One mini XLR microphone input - Mini-XLR to standard-XLR cable included - One 1/8 (3.5 mm) headphone monitor output - Includes two plug-in power condenser microphones - Includes device holder and aluminum hand grip. - Two 1/8" (3.5 mm) stereo line/mic inputs - One 1/8 (3.5 mm) stereo line output to phone - Volume control knob - Independent L/R level meters
The Smartmix is a microphone preamp that allows you to record up to 3 microphones to your camera or smartphone. The mixer also gives those DSLR cameras a headphone jack so you know what type of sound is coming out - videoguys.com.au
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videoguys.com.au
Basically it has two mono mic inputs (on the top) which work with the included two cheap condensor mics, but can equally work with lav mics or any unpowered mics and a mini-jack.
The side MINI jack can connect a Dynamic microphone or one needing Phantom power - so basically this would be good for a boom mic or any standard XLR mic.
All three inputs can be recorded at the same time, but there is no adjustment of individual mic levels, and all sound sources are mixed down to (mono? / stereo?) sound sources that would be digitised by the phone as a single (stereo?)sound source.
- Gear Guide - geeksuniversity.com
- Saramonic SmartMixer
- Manfrotto Light
- Adjustable Arms
Here is another review.
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geekazine.com