You can have a very well put together sound quality system that can have the ability to get decently loud.
My current setup for example, was designed with my music in mind, I listen to heavy metal, and wanted something that I could crank and it wouldn't distort, and wasn't out of balance...IE too much midbass causing muddy midrange, or harsh tweeters to the point my ears bled. The sub section is very nice it blends well with the levels I normally listen to it, and has the ability to get the hairs on my neck to stand up.
I don't think my setup would win any competitions, but that wasn't a goal I had in mind, I wanted to sound good to me, and not what someone else thinks sounds good, because I drive the car day in and day out.
Honestly, if you're concerned about sound quality at all, I'd dump most of your money into your front stage, if you know what you're doing, you can get most any subwoofer to give you respectable output. Though, when you're talking about mids and tweets, IMO if you start out with shitty equipment, your results aren't going to be as spectacular as say someone who spent a few extra bucks on quality mids and tweets.
Just my thoughts on the matter.
Oh, and I'm also changing my sub section around as well, ditching the 15 and going with 2 10s.