Some folks want to use the dedicated stereo outputs INSTEAD OF the normal LF/RF analog outputs from the multi-channel set due to the differences in their analog output stage -- the XLR connections for example. But when playing multi-channel content, the normal operation is that the dedicated stereo outputs receive a down-mix of the surrounds and center content in addition to the LF and RF content you'd expect them to get. This is fine if you want to use them to drive stereo speakers while playing multi-channel content (i.e., the surround and center content is not simply lost).
But it doesn't work if you ALSO want to wire up surrounds and center from the multi-channel -- i.e., there will be too much audio in the L and R to use them as just LF and RF.
In this new firmware you can set L and R so that they do NOT get a down-mix. That means they work just the way they work now when playing stereo content, but when playing multi-channel content they only get audio from the LF and RF channels. So you can use them as an alternate LF/RF when wiring up for multi-chanel without hurting their use for Stereo content.
NOTE: Folks mixing the XLR stereo connections with the RCA connections from the multi-channel will need to adjust in their pre-amp for the 6dB louder output of the XLR stereo connections.
NOTE 2: If side surrounds, center or sub are set to OFF, and the dedicated stereo outputs are set to work like LF/RF, then the normal down-mix that would happen into the REAL LF/RF pair will happen for them as well. E.g., if Center is set to OFF then Center content will be sent to them equally.