$1750 is a bit much. Havent ever heard of Kaption either, I would recommend against them. I will agree with Hootie, you should get more than 30watts per channel. Also, powering you rear speakers with just the deck is a bad idea. The midrange handle most of the sound in classical/jazz. If you look at the frequency ranges of the various instruments, few will spill over onto your high or low range speakers. Symbals and flute(piccholo) are typical of high range.
Now, the low range is a bit more tricky. This will take some tuning on your part to get it just right. You need an amp that will segment the signal such that the lowest range only goes to the woofers. I believe the most important thing you should look for is the ability to handle sound, not just the power. Also, when segmenting the bass, if you set the bass cutoff too low you will burn out your midrange easy.
I have found infiniti tweeters work well and arent too exensive. I havent ever used alpine speakers although the deck and amp I use are both Alpine. The other brands Hootie mentioned are all good. Add Bose to the list, they're a bit mnore expensive though.
One last thing, you got it right on the subwoofer. i wouldnt ever put anything bigger than a 10" in any car. Anything bigger than that gives too muffled a sound unless you put a lot of power to it. Think of it this way: when the string Bass is plucking a tune, it will sound like he's inside a booth(on a 12"). Now, you can let him out of the booth and rattle the car. But thats not why I like jazz. And certainly not why I like classical. Now, with a 10" you can put more power into it with less volume and get the sound of him actually plucking the strings.
2001 BMW 325XI, 60k miles
1993 Ford Ranger, 200k miles
1995 Ford Escort
1991 Ford Mustang
1986 Ford Taurus
1978 Pontiac Firebird