Ive got a Wahoo Elemnt, Kickr trainer, and Quarq DFour crank.
If the kickr and crank are both paired to the Elemnt, which power values are being recorded when im on the trainer - is there a way to select one or the other?
Id prefer to have my computer record my crank power, so its consistent with outdoor rides, but i need to keep the Kickr paired to control ERG.
I have had same issue and it can’t be done. If kickr is on it reads its power. U have to either dual record or do it all off the TR app. The power sync seems to be a TR exclusive feature
I’m not sure what the head unit reads. I currently only have the power meter paired to my edge as when the turbo was paired also it seemed a bit random. I only pair both the PM and turbo to TR as it’s more definitive about using the powermeter. Until I sorted it out the PM was dropping out (my cleats were about 1mm too close to the pod and touched it sometimes) causing power to be read from the turbo. My turbo lags behind the power meter at higher cadences and on ERG with the watts suddenly dropping 
By default I believe TrainerRoad software will use PowerMatch and record power from Quarq. However you should check device settings in TR app to confirm.
For checking after the fact, open the completed workout (I know this works on the web, not sure about apps), and if you scroll to the bottom of the “Power Zones” section, the power device used for the power data is listed.
Yeah, it’s tricky and not clearly indicated, but TR automatically pics the “BEST” source for any data if there are more than one of a give type connected.
If you have a smart trainer with power, and a power meter, TR is supposed to pick the power meter for data. You can force it to take the smart trainer by setting the power meter to “Cadence Only” in the Devices menu.
The only way to really KNOW what is being used it the method of checking that I showed above. That can fall short if a person is getting power dropouts. TR will swap behind the scenes at any point the “BEST” one is lost and there is a backup available. Could be confusing for some cases where dropouts are an issue.
One final adder, there have been a range of feature requests related to selecting or knowing the power data source. Could be worth reviewing these and adding your comments or +1 vote to any that are of interest.
