The EP4000 has a lot of dip switches on the back panel. Do you have them set right? Is the amp in stereo mode, parallel mode, or bridged?
You can take the minidsp and clean box out of the equation, one at a time, to see if one of them is the problem (you probably don’t need the clean box anyway).
If you pull the drivers of the boxes, put an ohm meter across the terminals and see if you get a reading. It should read roughly the impedance rating of the speaker (8 ohms, for instance). If you get no reading, the voice coil is blown and the speaker is toast. You might also try spreading your fingers evenly around the cone and gently pressing it in. If you hear a scratching sound, that’s another indication that the driver is toast.
Good luck, and get back to us.
Regards,
Wayne A. Pflughaupt