In order to create a merged profile :
Take a studio profile. Now, without altering any settings, take a Direct Amp profile (where there is an attenuating DI box between the power amp output of the amp you are profiling and the speaker). Now go back to the studio profile, bring the Cab section into focus and hit copy. Go back to the DA profile, bring the Cab section into focus and hit paste. Now hit Merge. Voila. A merged profile, which includes the original studio profile, the DA profile, and an accurately separated Cab portion, arrived at by subtracting the Direct Amp profile from the studio profile. This, by the way, is the only time the Merge option should ever be used. When adding a Cab to any old DA profile, you don’t need to merge. Only use it if you’re profiling.
With that all said, you are right about using Cabs from any studio profile that hasn’t been merged; here CabDriver will come into effect and the result will be less authentic than when using merged (separated) Cabs, although the results can be just as pleasing, if not more.
Does the KPA "remember" the last two profiles taken and is that how it "knows" which studio profile to subtract the direct profile from to calculate the true cabinet response? I think my mistake may have been to not take the profiles back to back.
The responses are much appreciated BTW. Thank you.