and I also measure the same results when I have done so, but its still important to keep in mind that the results you measure with an external meter do not tell you what the actual faders are doing. They report resulting change in DB level as measured by the meter plugin. The DB concept is a logarithmic concept in the way it is measured and reported.
A totally linear fader behavior will translate into a DB measurement that is logarithmic in nature. That is because of the way DB's are measured as a ratio, based on a reference level.
The VSL devs have already clarified that the actual faders in Synchron are using a simple multiplier using from 0.0-1.0, which is essentially saying a percentage of the amplitude. Nothing about DB's are taken into consideration while processing the CC faders. They simply apply a percentage of the amplitude and that's it. That is a linear response, in terms of the wave amplitude. However, a DB measuring device will report that linear amplitude response on a logarithmic scale.
We are talking about two faders here, they are as multipliers, which means the net effect of the two faders together is as follows:
dBFS = 20 x log10( multiplier)
However keep in mind that the above is not taking into account the reference level.
There is a lot of confusing information that is being circulated now on this forum about DB's in general, and the poster keeps moving his post to a new thread when I have tried to clarify these facts, I'm not really sure why other then it seems he really wishes VSL would add DB notches on the GUI next to the CC7 and CC11 faders...which is not in itself a terrible idea, but without having the notches there, the above comments will tell you what you need to know about these two faders. They are a applying a simple linear percentage to the amplitude. Linear Amplitude can be converted to logarithmic DB measurement using the above formula.
You can either compute both faders to a DB value and add them together, and also take into consideration the reference level..to arrive at the total final DB value... or you can multiple them together (as the first quote above), resulting in a final net multiplier, which you can convert to DB once from that, but also you need to take into consideration the reference level if you really want to do that right.
Its a lot of math juggling though. For me its quite enough to just think of the CC faders as simple multipliers as stated by VSL...they do that job perfectly. But I can see if someone is really used to keeping track of how many DB they are attenuating things or re-gaining back later, they want to know how much attenuation they are applying in terms of DB. It would be nice if VSL added DB notches to the GUI to show those cc fader changes as -dBFS attenuation also for that reason. so a person could set one fader to X number of -dBFS and fader2 to Y number of -dBFS and then set an external gain plugin to X+Y +dBFS to make up the exact same amount of gain.. theoretically. I get the point of that, but I also haven't found it that necessary actually know that or use it that way.