OK, I'll bite, and attempt to read through the fog. I think he's thinking that since you have to be careful about the amount of wattage your amp sends to your speakers, that the same thing might be true for an effects unit feeding into an amp.
OP: power is not an issue here. The effects unit does not send wattage into the amp. Technically the output of the effects can be described as voltage or other electrical terms, but for practical purposes, the output of the effects unit is pretty much the same thing as the signal that comes straight out of your bass. It might be a little louder, depending on how you have its volume knob set.
Actually, maybe he's thinking of using the Line 6 as a preamp to drive the power amp?
OP, if that's the case, then you need to read in my FAQ, there's an article that explains all about preamps and power amps.
There is nothing called "rack mounts". If you mean effects processors, or preamps, or other gear that happens to be rack mounted, then say specifically what you're talking about, because none of those things are known as "rack mounts". If anything, people would assume you meant the screws or nuts that attach the gear to the rack.
