Thanks again, Loraquest! I did not realize from the Sony instructions that there was a removable panel on the back that was covering more connections. I had searched through the instructions but did not find any reference to an IR input, so I am glad that I saw this thread and you called my attention to the IR input.

I experimented with inserting a stereo cable all the way into the IR input on the TV and various depths into the MRF-350 but could not replicate your finding. The stereo cable that I used has a "bulbs" in the cable a few inches before each plug, so perhaps they are limiting the signal in some way.

I also tried a special cable that I bought with an eye toward establishing an RS232 connection to the TV from the MRX-2 that I expect to receive on Thursday.

This cable has a 3.5mm plug on one end with three stripes on it, and a plug on the other end with two stripes (a stereo plug).

[Link: homecontrols.com]

I plugged the three-stripe end into the TV and the two-stripe plug into the MRF-350 and found that the TV was getting a signal with the plug partially inserted into the MRF-350. I assume the TV is just ignoring whatever its coming through the extra stripe (if anything).

I am hopeful that the cable will work for RS232 control through the MRX-350 so that I don't have to buy any more cables or adapters.