johnbeez

You need a pair of insert cables. Here's a link: http://www.zzounds.com/item--HOSSTP20?siid=89890&-yFgSJADikZgg0jhyfRUMXplg7gT7IBhYtI1-hAhgMD2pnTIZzterpBoCwCLw_wcB=

The Epsilon Inno-mix has a Mini Innofader and is powered by 5V DC. You could easily make it portable with a USB battery. http://a.co/h5Qg7UO

For a momentary switch start/stop you can use one of these Polulu boards (low voltage model). https://www.pololu.com/product/2808 Silent and solid state. Works really well, the only downside is if you are also running an ultrapitch board this will make a speaker pop when you start the motor. Haven't bothered to find a fix for that. I just run it without the PWM ultrapitch.