The MXL MM-4000 Mini Mixer + is a portable recording interface for mobile phones, tablets, DSLRs and computers. With it, you can record audio to your device using multiple microphones, or convert your electret mics into USB mics. The Mini Mixer + converts four electret microphones to mono output for use with mobile devices and computers. The Mini Mixer + has independent gain controls for each microphone, plus headphone monitoring and line level out. The adjustable line level out allows you to record to mobile devices and monitor audio from the same jack. The Mini Mixer + also has a USB in and out for audio playback and recording to your computer. The Mini Mixer + is portable, compact, and gives you multiple power options: batteries, a USB bus or USB battery pack.