Preamp with integrated amp

I know many topics have been posted and Paul also posted a video. I have a SET tube amplifier which is integrated however I am sure the preamp is passive just the volume control and inputs. Other than that the usual input stage tubes, and output power tubes with their respective transformers.

I emailed the factory who said that I could hook up but im concerned about distortion, noise etc

Won’t the preamp tubes in the preamp conflict with the input stage tubes in the integrated. How would I balance the output on both ?

Ps - the amplifier I have sounds fantastic 3.5w/channel of pure audio nirvana but I was curious what a preamp might do further