Hi,tube amps are not a peice of gear that your going to find at a regular electronics store,tube gear is a botique item & your going to have to either look up local hifi dealers who cary tube gear or buy the gear over the internet,audiogon.com is the best place to fine both new & used tube gear from dealers & private sellers alike,i strongly reccomend buying any high end gear used as you will save about 50%.
With that being said i will explain the differences & pro's & cons of tube amps starting with the cons.
Tube amps are not made for every speaker system,speaker impendance is very important in matching the speaker to the amp,for instance a speaker with a nominal impendance of 8 ohms where the impendance dips to 4 ohms would not be a good choice,tube amps work their best with speakers that dont have large impendance swings.
Biasing the tubes requires a basic understanding of the use of a multimeter & you must rebias the tubes every so often,this is not a hard thing to do but if it is not done & done right it will lead to premature tube failure & lousy sound.
Most tube amps will give you a weak bass response,forget all the crap that tube amp owners post on the internet about their 40 wpc tube amp giving them the best bass response that they have ever heard beacuse its simply not true.
The cost of buying replacement tubes can be huge especially if your amp is running kt 88's or kt 90's & dont even think about trying to buy any nos genelex tubes because you'll need to take out a loan in order to buy them.
Tube amps run extremely hot to the point that they can burn the skin on contact or start a fire if not attended properly,placement within a rack is not possible with most tube amps especially high wattage tube amps that your thinking about buying.
Now for the good things about tube amps.
Tube amps clip differently than a solid state amp,most tube amps will continue to produce wattage through a full clip & are less likely to blow a driver from clipping over the same wattage solid state amp.
With tube gear you can try different things to tweak the sound such as tube rolling(big bucks) though but fun still.
The beauty of a tube amp is unbeatable & adds greatly to the enjoyment of most peoples systems,its nice to see the soft glow in a dimly light room while listening.
I own both tube gear & solid state gear & i love both kinds of gear but if i were in your shoes i'd be looking tword buying a great solid state amp as opposed to tube gear,for the cash your going to need to spend on a 200 wpc tube amp you could get a lightly used mid level high end class a amp or a top level class a/b solid state amp from krell,mciintosh,plinius,pass labs ect & all these solid state amps will blow the doors off any tube amp of comparable wattage in sound & overall performance.
Quality solid state amps are a much better way to go for most systems over tube amps,solid state amps will give you a much better bass response over tubes & speaker matching is less importantwith solid state because the amps are not as easily effected by impendance swings ,tube amps are geared more tword the type of people who enjoy tweaking a system & listening for minute changes in sound because tubes are not a plug & play type of device.
A quality tube amp with a 200 wpc rating is going to cost quite a bit of cash,a 200 wpc tube amp is considered to be extremely high powered,below are some examples of 200 wpc tube amps & some examples or what the same amount of cash can get you with solid state & in each case the solid state amps i used as examples will kill every one of the tube amps with comparable wattage ratings.
Tube.
http://cls.audiogon.com/cgi-bin/cls.pl?ampstube&1163519234
Tube.
http://cls.audiogon.com/cgi-bin/cls.pl?ampstube&1163176913
Tube.
http://cls.audiogon.com/cgi-bin/cls.pl?ampstube&1163169866
Tube.
http://cls.audiogon.com/cgi-bin/cls.pl?ampstube&1162664287
Solid state mcintosh .
http://cls.audiogon.com/cgi-bin/cls.pl?ampstran&1163271800
Solid state mcintosh .
http://cls.audiogon.com/cgi-bin/cls.pl?ampstran&1161460431
Solid state krell .
http://cgi.audiogon.com/cgi-bin/auc.pl?ampstran&1159495538
Solid state krell.
http://cls.audiogon.com/cgi-bin/cls.pl?ampstran&1163282594
Solid state plinius.
http://cls.audiogon.com/cgi-bin/cls.pl?ampstran&1162693288
Solid state pass labs.
http://cls.audiogon.com/cgi-bin/cls.pl?ampstran&1162166307
Solid state rowland.
http://cls.audiogon.com/cgi-bin/cls.pl?ampstran&1161837581