For all you users of 2.9's and 3.3's you need to be aware of something... The design of the crossover for these speakers has the midrange and tweeter connected in REVERSE POLARITY... this is true of the AC2 and the L5, M5, M6, T5 and T6 systems as well. This means that ANY speaker BESIDES those listed above will be OUT OF PHASE from the croosover region of the woofers(approx. 350hz) on up! NHT recommended connecting the AC1/2.5's/1.5's/etc. in REVERSE POLARITY when used in a system with the 2.9/3.3's... the problem there is then the BASS freqencies from 350hz on down would be OUT OF PHASE. Tho bottom line is that if you are using anything but the AC2/M6 with your 2.9/3.3's you will experience poor/indistinct imaging OR lean bass response due to PHASE CANCELLATION depending on which polarity you have the speakers connected. Obviously the AC2 is the IDEAL choice, but the new EVOLUTION speakers utilize a similar design with slightly different crossover points.