I have a Kenwood 8452 (800W max) running 4 6.5 Focal speakers. To hear them @ 75ft I have to have the head unit (CMD4) turned all the way up/max volume. The amp has sensitivity controls but no gain. Power is directly to battery, speakers are bridged for 200w X 2 and all connections are tight.
Something's not right as I have the interior speakers (polk 6.5) and a sub powered by a Clarion 480 that will break your eardrums at half volume.
You need to turn the sensitivity down to a lower number. I know it sounds wierd but that's how the kenwoods work. I wouldn't turn it lower than 1.5 or the amp will probably cut out.
notidad, those "sensitivity" controls ARE the gains. The lower the number, the higher the gain. .2 volts would be full gain, and 4 volts would be no gain or whatever the numbers might be.