Believe me, they overload with standard SPSPSB1 battery box, at a Velvet Revolver gig, half way back on the floor.
With the three-wire mod and battery box, they sound lovely!
By the way, although they don't make them anymore, it's possible to make your own:
Buy the slimline CMC-8s.
Buy the adaptors:
Trade the small 943 card caps for AT853s.
That's how I built mine, anyway...plus this way, they have the groove in the body for the mini rotating clip.