A normal pentagonal prism has 7 faces but presumably Mojo envisioned leaving the floor and back "speaker free" and therefore he would have 5 faces with 5 M3's each for a total of 25 M3's, or 5 ADA-1000-5's (one for each face). However, unless each M3 needs a discrete signal, you could probably wire 5 M3's into each channel of an ADA-1500-5 for a mere $4,400.