If you call a pro, he can spend a few hours troubleshooting.
Or, he'll just replace the KP2s.
Prob bad trim potentiometers (trimpots) for the volume leveling. I don't know much about that, other than you reduce the level with the power off, turn it on, and then adjust the trimpot screw to increase the level.
I'd play with the trimpot screws more, redo all the speaker connections at the KP2s and redo the connections at the speakers. Re-read the manuals. Get a magnifying glass and visually inspect the punch-downs, if you don't feel like learning how to do it. The manual says it is a 110 punch down - fixed blade 110 punch down tool at HD/Lowes is $15, no wire stripping necessary. Don't let the fancy words fool you - once you see how it's done, you'll think 'oh, that's so simple.'
A 110 punch down uses an IDC - Insulation Displacement Connector. The wire, with insulation intact, is positioned over the IDC connector. The tool is then used to push the wire down into the connection, into a metal slot. The slot cuts into the insulation, making contact with the wire/conductor. The 110 tool includes a blade which cuts the extra wire which is hanging out of the side of the connector.http://www.molex.com/tnotes/idtbm.html
How much is your time worth?