49 minutes ago, patric_o said:
Say I were to buy two of the same 4 channel amps to power the six to eight speakers in the vehicle. Would this idea I have of an echo be something I would have to come up with a fix for?
In my experience installing car audio setups, you'd be more prone to notice humming or hissing if both the amps were using different grounding points, or maybe have a delay if your RCA inputs from your head unit were of absurdly different lengths. However, I ran a full set of Alpine Type-R's in my 2003 Toyota Corolla, plus an 8 inch sub in a custom enclosure, and had no problem with a 4 channel amp + a mono-block subwoofer amp.
The only thing I had to resolve was hiss caused by using a Y-splitter on the RCA inputs to provide an input for the subwoofer amp because my headunit only had 4 channel output built in. This was easily solved by adding a ground loop isolator to either the RCA's feeding the sub amp or the 4 channel speaker amp. (I can't remember which.) I still have my setup sitting in storage as I replaced that car, but yeah you should be fine to run both amps.
Just make sure you use an appropriately sized fuse if running a single 4 gauge power cable from the engine bay, along with a fused power distribution block, too, then ground both amps to the same point on an unpainted surface of the car. Run your audio cables (speaker wire + RCAs) down the opposite side of the car than your power cable to eliminate noise/interference, and pickup some sound deadening material if your car has rattling panels.
Any other questions, just quote & reply here; happy to help! Take pictures along the way, and share your progress with us.