which should i purchase (tetra or sonus faber)

I like Tetra speakers very much (though I haven't heard the 606 yet). Sounds like you like 'em too. Seriously I doubt there's a wrong choice between the Tetras and the Sonus Fabers, but why not get the one that your ears say are "without a doubt the most musical detailed speaker" you've ever heard?

Duke

good advice audio thanks, if you ever get a chance 606,s something else