Hi Alan, thanks for your response. Mine is an experiment. It is a high quality "summing box" (for Mike). You're right, it will raise the noise floor a bit but it has a beautiful sound. Just because I don't want to make substantial changes to the 4K I asked if it could be added to the rear buses (since in the vast majority of cases, like mine, they are not used). If it was a feasible thing and if so how. That's all. Maybe, as soon as it's installed, I'll upload some tests on the forum and we'll all evaluate the difference. If it was money wasted, I'll implement it in something else.
Thanks!