Nope. That's not how electricity works. Using the term "juice" is kind of where it falls down Technically juice probably should be power (V x I)

Current flow is determined by voltage and impedance (resistance for a linear circuit). V=IR. Increase the voltage into a fixed load and current increases proportionally.

The amps present only a very small load (impedance) on their remote lines (which is the whole point of having them so they don't excessively load the head unit). The amplifiers will draw only enough current on their amp remote lines to power up the amp. Internally they'll have some form of switch that turns the rest of the amp on (which then draw most of their power from the +12V battery connection). Typically this would be of the order of mA or maybe 10s of mA.

To put it another way, the power (juice) supplied to the load is as much dependent on the load itself (the impedance) as it is the supply (the voltage).

So the only way you'll supply too much "juice" to amps would be by increasing the voltage significantly, in which case the rest of the car would probably blow up too