I just installed a D4000.4 amp and DB6501 speakers. I'm looking at the instructions for tuning the amp and it's not making sense to me. In step 5, it says "turn up the level control corresponding to the midrange output...", again for the tweeter in step 6 and finally for the woofer in step 10. There are not separate tweeter, midrange and woofer level pots on the amp. What am I missing here?