My son owns a pair of Def Techs and they sound incredible. I have had several Axiom speakers over the last few years and while they were not bad, I ended up replacing them. The nice thing about towers with powered subs is that you can still get a seperate sub and set the towers to small. This way you get the flexibility of a seperate sub for movie watching. But when listening to music in two channel mode, you get the bass in the main speakers. I did this for years and loved the options. I used my sub for movies, and then turned the effects off and listened to two channel stereo music through my Infininty Overture 2's which had powered subs. I have since changed my setup, but it worked great for me.
Albert kind of hits things right. It seems that most audiophiles will tell you that they want all the sound coming from the mains. They say it is purer quality on certain kinds of music. This even I can understand. I am not knocking Def Tech.. as I owned a good set of them 4 years ago with built in subs in the front and I had dipoles in the back. Everything was powered which is a pain in the butt but one can live with that. I did enjoy them when I had them. Most of my use is HT and this is where I felt they fell very short.. Others would call that crazy as they really are built I think mostly for HT users. Anyway I make a change to a bit bigger mains and centers, I had floor standers for direct radiating on the sides and later decided I didn't like that for movies and went back to dipoles from a different company. Anyway I added a big SVS sub and could not be happier with my new set up (you can PM me if you wish to know what everything is as I don't want to start a war over brands here) but the main thing I am saying here is that everyones room is different and more important everyones ears and tastes are different so there is no really right and wrong here if you cover the basics.
I couldn't agree with you more. If I was building a HT and was going to primarily listen to movies, I would not buy mains with powered subs. I would go with a seperate sub. If I was building a system for music, I would not go with a seperate sub, but would go with powered towers. If I was building a system for both, then I would buy both! Money being no object of course.
AlbertD... there are a lot of good speaker systems out there that are killer for music even using a small sub just for those super low times. I agree with you as well but if I was buying an audio only system I would not completely discount a small fast firing closed port sealed sub. I don't have the room for both, or two systems or I would go for it. The speakers I have are towers and big center and huge sub does a decent job at music as well and will have to do for me unless we ever move..... hum... the kids are just about in college.. maybe then... haha. But you are right if one has the money and there are a lot that do just that have two systems. Visit the forum over at av123.com and you will see many that have dual systems and would not have it any other way.