I looked at the Turbosound TXD218s, Soundbridge 218s and numerous other high quality dual 18 subs. The SRX728s can take 4000 watts easily. With a SPL sensitivity of 98db at 1 meter the 4000 watts yield 134 db. Using two TXDs at 1200 watts each you get 132 db. So, while one SRX728 costs more than one TXD, it is much less than two TXD218s. Also you get half the weight, half the space, and half the cabling. Then there's the sound. Nothing short of line array subs goes as deep or as loud or as solid. Nothing. Using the SXRs as part of a mid-size venue array system was awesome. Using 2 SXR728s and 2 JBL Array Series 4892s per stack and 2 stacks per side of the stage, using one Crown I-Tech8000 per stack for the subs and one I-Tech3000 per stack for the Arrays, we covered 9,500 people with incredibly clear sound.