Manufacturers build some excellent extension cabs but, most of the time, you have to take whatever speakers they've selected for that cab build. When you build your own cab or order a custom built cab you can select from multiple speaker sizes, layout and brands / models of speakers utilized. I'd like you to think about .... 1st .. the number of and size of speakers. The poll is for that. After making your poll choice I'd be very interested in the brand and model of speakers you would use. Celestion, Jensen, Eminence, etc. . Alnico or ceramic magnets. A mix of both? Specific models from your selected brands?