Interesting historical tidbit: around the time the Model 950 started shipping (with inputs and outputs that are if anything slightly closer together than the 990's), Outlaw revised the design of the PCA's locking connectors to reduce the diameter due to feedback of this type. The current size are almost indistinguishable in diameter from other locking RCA's I've got in my system. Locking RCA's are inevitably a tight fit, whether from Outlaw or from somebody else.

EDIT: Woah, post number 6000...