the 99 is the evolution of the 100 and each speaker requires very little power to play loudly...the speaker components and cabinets are different. if you like a detailed but meaty robust presentation then VS speakers are for you. I own the 99's and have them in my home theater using a 100 watt per side ss amp but formerly used them with an 18 watt set amp. the 99 is a really good loudspeaker.