Your assumption is correct.
The remote is the same between the two units - setting the DAC to "variable" allows remote operation, as does setting the amp to "remote". You obviously don't want to set them both for remote operation because they will both change each time you hit a button.
Honestly I haven't used "variable" on the DAC much since I've been using it mostly as a pure DAC or DAC/integrated headphone amp rather than as a pre-amp. I'll get around to that ASAP.