Some people use regular Bookshelves (direct radiating) for surround or rear channels, especially in the past. Personally, I like Axioms quadpolar design as you are SURROUNDED or enveloped by the sound. Also you don't have to be in the sweet spot when using this design to enjoy the full benefit. I would recommend you reading Alan from Axiom's technical advice areas link below from the main website.

The Inside Dope on Surround Speakers


M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85