Not sure what "hydro" is in reference to your issue, but I'm guessing you want to put speakers in a compartment, and those speakers are driven by your dash radio. I'm sure it can be done, but I wouldn't want to deal with the wiring. (If my assumption is incorrect, I apologize)
When I bought a new sound system for my home, I took the old receiver, CD player, amplifier and speakers and stacked them in the cabinet behind the passenger's side front wheel and strapped them down. On my coach, this cabinet is pre-wired with a power outlet and an antenna/cable connection for a TV. Now I have an outdoor entertainment center and don't have to go inside to operate the system. You could always put a good old boom box in there too!