Audio Systems: Sound Quality VS SPL, component speakers, range speakers

Question
Hi Mark,
  I read the reviews on the Polk DB6500 and thats probably some of the cheapest speakers I've seen and the reviews are very encouraging.  I just have 2 questions.
1) With any set or sets of midrange component speakers (1 set of seperates for the front and 1 set for the back), should I power them with an amp in any case even if I don't have a sub.  I heard just having an amp enhances the sound on any speakers.
2) What do you think of Massive Audio or Kicker as opposed to Polk?  Would you recommend them?  Or do you think they're a little overpriced for the reliability and quality of sound.  (This question is purely for your opinion)
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Followup To

Question -
Hi Mark,
  So I've been looking around the internet searching for a site that give comprehensive ratings on sound quality of speakers.  I had a couple of mid range component speakers blow out on me recently after 2 years.  And I'm really looking to buy a new set of speakers that have a very clean sound (without just bass) but are affordable.  And it's confusing because an installer friend of mine tells me to go with JL's and a coworker of mine's husband also does car audio and she says the JL makes horrible sound quality mid range speakers.  So I'm trying to get the most bang out of my buck without going extremely high end or low end.  Could you give me an idea of what I should do?

Answer -
well part of the problem is that audio in general is highly subjective to weather it sounds "good" or not.  so everyones opinion is different.  What I have found is that on www.crutchfield.com you can find the polk DB6500 components and theres something like 65 reviews all with 5 out of 5 stars or at worst 4 of 5 and they are only $199

take a look at them and tell me what you think.

Answer
to be completely honest I've never actually heard any of them.  but I dont see the incredible reviews on the other speakers that I see on the polks. Never been a fan of kicker, massive has some nice stuff but like I said the polks have rave reviews for their price class.   Typically I recomend an amp for componenet speakers even if not running a sub.  reason being is that the passive crossover sucks up power and they do in fact sound better with more muscle behind them.  try to find an amp that matches their RMS rating as close as possible.  a little over is ok (125 if rated for 100) exspecilaly if using the amps hp crossover to filter out 50 and below or even 80 and below when pairing with a sub.  
Good luck!