Center Channel on an Integrated Stereo Amplifier


Background: I have an integrated 2 channel amp for stereo listening. I added a sub to it with a direct connection to the terminals on the back of the amp (2.1 setup right now). 
I also want to have a Center Channel that I can connect and disconnect when I want (so I can listen to the 2 channel for music and have the center channel connected for movies). I have a really good amp, so I would love to be able to use that amp to power the speakers when watching movies (and power the center channel too if possible!). 

Question: What is the best way for me to get this done? 
For me to have a 3.1 setup - a 2 channel integrated amp with 2 speakers, a sub, and a center channel WITH connectivity options so I can disconnect the center channel whenever I want. 


Thank you all for your help,
Shawn 
128x128shawnpmathew
to me it often sounds great at first, but after a few hours, much less great...
A 3.1 or 3.2 setup can work really well.

But I'm not clear on how you are processing/sending a true center channel signal and which amp (or amps) you are using? Can you elaborate?
@jl35 - I do sit between the main speakers. They are set up now pointed in toward a sweet spot. 
Thanks for the advice
@david_ten - I do not have a processor to send a true center channel signal to the center channel. That's why I am asking the question, so someone can guide me on which processor can do what I am looking to do. 
I have a pair of ML speakers driven by a PrimaLuna DiaLogue Premium Integrated amp, and I also have a REL R-505. That is my 2.1 setup. 

I want a  way to add another channel (a center channel) to this setup.