Ultrasonic
Addicted to Fun and Learning
Thanks—yes, it really seems no better than a passive volume control, and considering the amps on the market with input sensitivity higher than 2 VRMS, seems like a significant limitation.
You're right that it is a consideration for people to be aware of but I'd suggest that for most it will not be a practical limitation. Also, there are pros and cons of each type of volume control - traditional analogue pre-amps aren't flawless, or free.
Where signal level is an issue for the main speakers I suppose it would be possible to use a fixed gain pre-amp (or one made so by just not adjusting the volume knob) between the Flex output and the power amp input. I can't see this ever being an issue for an active subwoofer due to their own gain controls.