Which Events are send exactly? Channel 6 would mean that something is wrong with the 6th pot of a 16-pot row (assumed that you’re running the MIDIbox with the default setup). It’s very easy to determine which pots are affected. The first row sends reverb by default, the second chorus depth, the third cutoff, the fourth volume.
Hey - you shouldn’t have to filter that data with midiox. If you have your stuff set up properly, you shouldn’t get any random midi events. Have you also grounded all unused inputs on the AIN module? All those midi events are likely to clog up your midi transmission, even if you filter them. Do you have all of the chips stuffed on the AIN?