I know what you're asking. A pro encoder is for broadcasters and would not be included in a consumer device.
Even the original Orban Optimod TV did not include SAP. And then it is not a modulator.
The SAP encoder was marketed as a separate device.
There are modulators out there for stereo such as the Radio Shack 15-2525. I see them on Ebay every so often.
Then there is the Channels Plus 5601 which is an encoder that can be connected to any modulator.
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