TOPIC:

Quick question: Can a TS to RCA adapter be used to convert the balanced output of the Flex to unbalanced RCA to connect to a subwoofer? Would I expect better performance using a TRS >> RCA adapter? Thanks in advance.

I think you would use something like this  
in my experience connecting subwoofer in stereo produces better results

The Flex balanced outputs are TRS not TS.
I would use a cable as suggested by @kenken, but just one leg of it.

A TS to RCA cable would ground one side of the active signal on the Flex output.  (It's preferable not to do that.)

Dave.