1 set of pre-outs for multiple amplifiers. How it's done.
Ok, so your head unit only has one pair of RCA line outputs, and you want to run multiple amplifiers, or multiple amplifier channels, and you want to know how to do it, and do it right.
right?
well here's the simple answer.
If you want to run a single 4 channel amplifier, you can use Y-splitters and get inputs to all 4 channels, but the downside is the loss of your ability to fade front to rear from the head unit.
next, better solution:
you use a preamp, which mounts under your head unit, and takes one set of inputs, then splits that to a pair of subwoofer outputs, and a set of front and a set of rear outputs, while giving you at-the-dash control over fading, balance, and subwoofer volume level, usually along with 3 or 5 bands of EQ adjustments.
The next solution is to use an electronic crossover, which will allow you the most control over the amplifiers connected.
With one set of inputs you can split to as many as 7 separate amplifiers with clean, line-driven signals allowing for control of phase, output level, crossover points, and individual slope for each channel or pair of channels.
Products such as Audiocontrol's 4XS and 6XS, Orion's 300CRX, and Coustic's XM-3, XM-5, and XM-7 are but a few examples of electronic crossovers that are, in my opinion, the best solution to this common problem.
They are also surprisingly affordable if you shop around for the right product to fit your needs.
