First off, audio and acoustics aren't my area of expertise so to speak so forgive me if I seem a bit slow on the issues of sound but I am looking for a decently powerful but clear set of speakers. The only real qualification is that it needs to be 5.1 and that it should cost no more then 100$ USD. I was considering the Logitech x540's although they are no longer produced and not always readily available (plus I should see what the community has to say about them). I also considered the Logitech z506's but many consider it to be a downgrade to the x540's so I just figured that a second opinion should be in order. Any help would be appreciated and thank you.