Thanks MC.
Yes, I'm sure the signal was arriving already distorted. The Daking preamp is just a preamp, as you could imagine. The -12db was the level going into my DAW according to the input meters of Studio One 5.
So I was using too much gain at the Daking preamp stage.
In the end, I couldn't understand ch9. So I just used TRS input 1 on the back of the UFX II which seemed to have a 0 to 12 db scale of gain.
I really apologise because I am not conversant in all the figures and terminology.
All I want to do is connect an external preamp to the UFX II.
EDIT: I was just reading about the Daking MicPre/eq...and it appears I was using it very wrong. It has an output which is a passive attenuator. Which means it can attenuate the signal after the preamp/ eq stage. Correct use should have the output knob set all the way up...so that if need be later you can attenuate. Once the output knob is set all the way, you then increase at the gain knob until the desired signal level is reached.
I was using it by cranking the gain way too far and then dialling back the output to compensate. This will lead to distortion.
This is one of the problems I had.
Fireface UFX II, Babyface Pro, Windows 10, Studio One 5