Does anyone know if it’s possible to get input from a playstation controller whilst still having that input go through to the console?
The idea being you could play a game normally whilst also controlling musical paramters. What would this need?
I think the solution is not straightforward. You need to dive into electronics a bit for that.
If you have a wired controller, then it will be powered by the playstation. You can’t just "tap into" that circuit. One option could be to wire low-resistance opto-couplers (http://en.wikipedia.org/wiki/Opto-isolator) into the signal cables and connect a 2nd circuit board like an arduino (http://www.arduino.cc) to it. To put it simple, an opto coupler could be seen as a "signal duplicator".
Check the arduino site, they have a section on psx controllers: