I recall a reading a thread that spoke of some kind of splitter I could use to still use my BOSE system as well as add a sub (or an amp in this case). From what i remember, it looked like a box with 3 sets of wires, one to plug in the wire from the HU (female) and 2 other wires to connect to the BOSE amp and another amp.

My current setup consists of a Pioneer HU that unfortunately doesn't have a dedicated subwoofer channel, so that's why I'm forced to do what I'm proposing. The HU is connected to the converter (an assumption since it came like this when i first got the car and I have yet to open up the dash to take a look, though everything works fine) that will turn the signal back into one suitable for the BOSE amps to process (forgive the lack of more technical terms).

Right now, my rear left amp is busted (I'll probably fix it up next week), but what I want to do is tap into that signal and add an amp to it for my sub while still retaining use of that amp. My thinking is that this will allow me to add an amp without replacing my entire system (which is not an option right now) and if I need to kill the sub, I'll just not give a signal to that side.

Anyone have any idea on what this splitter I remembered seeing can be found at or have another way I can add a sub?