I have not found a video from you in this thread. Can you post it again?
About taking analog ODs on the input: Over the years there have been hundreds of confirmations (because many people ask if it's good) that the Profiler - and any other digital modeler - take analog pedals without problem.
I know dosens of players personally that I talk to frequently, that use analog ODs with the Profiler since years.
The Clean Sens is not a hurdle for that. However, changing Clean Sens on the fly will change the boost of the OD, just like changing the ODs volume. That's a natural fact that cannot be avoided, but by leaving Clean Sens at zero or at an other preferred setting for the time being.
If an OD does not sound good with the Profiler, it might be about the Profile used. We could step into this topic further, if you like.
About headroom issues: What issue exactly are you referring to? We had at least 3 independent topics.
I use a greer lightspeed and an old silver klon in front of my kemper, IT sounds FANTASTIC,,also a POT ,They work just like they do in front of my matchless,, princeton, and morgan AC20,,it takes analog pedals PERFECTLY,,,,,,Just like an amp,,