Terryn: I think the battery PS takes it up to a different league. I won't hesitate if I could do it over again. The batteries used are the seal, deep-cycled ones. Since my mono's are customized units, they come in as a 4-piece configuration. However, I don't think this is standard. If memory serves me right, Jack's battery chassis comes in 24" x 12" x 12" military metal ammo case. Users have the freedom to use the amps with and without the battery. With the battery turns on, the noise-level drops further, the soundstage expands, the weight and the "density" of the sound images improves, everything just gets taken up a couple notches or more. It is not as much as an arch-welder like GT-800; luckily none of my speakers runs around 1 ohm, so I don't need it. Sonic-wise I believe it is the best that Paul has to offer (for now). :)
Howard