So, I'm trying to put together a decent HOTAS system, but I really love my T16000 which does not have an attached throttle. If I had an X52, could I use just the throttle quadrant along with my T16000M? Specifically, do I have to plug the X52 joystick into the X52 throttle...Thanks!

Specifically, do I have to plug the X52 joystick into the X52 throttle...

Yes it has to be plugged into the X-52 joystick its got a custom Din plug on it not a USB cable. There is nothing stopping you hiding the X-52 stick under the desk somewhere and only using throttle, you don't have to assign anything on the Joystick if you don't want to, just remember to remove the default assignments on the X-52 joystick first then if you bump the stick by mistake it wont interfere with your other stick.To be honest though once you try the X-52 stick you will probably throw the T1600 in the bottom of the cupboard as a backup.