The surround speakers in a 5.1 system are not about 'impact' they are about immersion. They don't really make your system louder. They normally play at a low level compared to the front stage speakers. 'Impact' belongs to the front stage speakers and subwoofer. At a 1.5k budget there are a lot of good choices, like Ascend Acoustics, Monoprice Monolith, SVS, RSL, but if you are after impact, I would be looking at the Hybrid 3 3.1 system from Hsu Research, that gets you a serious 15" sub and three horn-loaded bookshelf speakers, that will have a lot of impact for just under $1500.