[Zippy]

From what I see, your issues with the polk components is due to under powering them. They are rated 125 watts and you are putting 65 watts to them. This will cause what you are describing, no mid bass and shrill highs. Replacing the Polk with Morel will get you more of the same problem. If you want them to sound like they should, you are going to have to replace the audison amp. Since you are using JL amp for the sub, take a look at the JL HD600/4. Your installer should keep the gains way down on the 600/4 and maybe decrease the signal in at your head unit. It will sound way better than it has. You will have mid bass and your tweeters will not sound shrill.

The Alpine head unit has the ability to run full active. You can isolate the frequencies for your tweeters, mids, and sub at it before they go to the amps. Front RCAs will be tweeters, rear RCAs will be mids, and sub RCAs will be sub. I'm thinking your installer did this. It will sound better than using passives crossovers with the physical distance between your highs and mids. However he did not take into account the lack of power.