Even an 8' sub would be enough kick compared to a set of 6x9's, but in saying that will the 6x9s fit or only 5x7s?? but a nice clean sub with a descent set of clear speakers does the trick. Nice choice with the Focal Utopias, wont need rear speakers with those. all round top set up. Looked up LHRX Studio, old mate has some descent gear, be sure to head down to the shop when Im down that way. Looked into the the Audison Bit.ten processor that Boog72 recommended, if the Audiocontrol LCQ1 isnt what im after I'll give the Audison processor ago. I personally wont recommended anything but Rockford or Alpine Subs, amp wise yeah the Alpine PDX range are awesome, but Ive used Rockford amps since I got my licence and havent had any problems and more then happy with the quality so going to stick by them